Human amylase gene copy number variation as a determinant of metabolic state

Natural hypoglycaemic bioactives: Newer avenues and newer possibilities

The incidences of endocrine and metabolic disorders like diabetes have increased worldwide. Several proposed molecular pathways mechanisms for the management of diabetes have been identified, but glycaemic control is still a challenging task in the drug discovery process. Most of the drug discovery processes lead to numerous scaffolds that are prominent in natural products. The review deals with the natural bioactives as an α-amylase inhibitors, α-glucosidase inhibitors, protein tyrosine phosphatase-1B inhibitors, dipeptidyl peptidase-IV inhibitors, G-protein coupled receptors-40 agonists, PPAR-γ agonists and the activators of 5'-adenosine monophosphate-activated protein kinase and glucokinase. So, in this review, we focused on the hypoglycaemic bioactives, which will assist scientific developers, traditional medicinal practitioners, and readers to discover some potent antidiabetic molecules. Strategies like chemometric approaches, scaffold hopping, and total synthesis of natural products by group modification or ring opening/closing mechanism could be useful for the development of novel hit/lead antidiabetic molecules. The study concludes that each phyto molecule inherits a potential to get explored by repurposing techniques for various antidiabetic targets and offer an alternative antidiabetic therapeutic medicinal potential.

Detection and enzymatic characterization of human saliva amylase

As a rule, an experiment carried out at school or in undergraduate study courses is rather simple and not very informative. However, when the experiments are to be performed using modern methods, they are often abstract and difficult to understand. Here, we describe a quick and simple experiment, namely the enzymatic characterization of ptyalin (human salivary amylase) using a starch degradation assay. With the experimental setup presented here, enzyme parameters, such as pH optimum, temperature optimum, chloride dependence, and sensitivity to certain chemicals can be easily determined. This experiment can serve as a good model for enzyme characterization in general, as modern methods usually follow the same principle: determination of the activity of the enzyme under different conditions. As different alleles occur in humans, a random selection of test subjects will be quite different with regard to ptyalin activities. Therefore, when the students measure their own ptyalin activity, significant differences will emerge, and this will give them an idea of the genetic diversity in human populations. The evaluation has shown that the pupils have gained a solid understanding of the topic through this experiment.

Anti-Incretin Gut Features Induced by Feed Supplementation with Alpha-Amylase: Studies on EPI Pigs

The acini-islet-acinar (AIA) axis concept justifies the anatomical placement of the Langerhans islets within the exocrine pancreatic parenchyma and explains the existence of the pancreas as a single organ. Amylase has been suggested to play a key role as an anti-incretin factor. Oral glucose tolerance tests (OGTT) were performed on 18 piglets in both a healthy (prior to pancreatic duct ligation (PDL) surgery, study Day 10) and an exocrine pancreatic insufficient (EPI) state (30 days after PDL, study Day 48)). Amylase (4000 units/feeding) or Creon® (100,000 units/feeding) was administered to pigs with the morning and evening meals, according to study design randomization, for 37 days following the first OGTT. Blood glucose levels, as well as plasma levels of insulin, GLP-1, and GIP, were measured, and the HOMA-IR index was calculated. EPI status did not affect the area under the curve (AUC) of insulin release, fasting insulin levels, or the HOMA-IR index, while amylase supplementation led to a significant (p < 0.05) decrease in the above-mentioned parameters. At the same time, EPI led to a significant (p < 0.05) increase in GLP-1 levels, and neither amylase nor Creon® supplementation had any effects on this EPI-related increase. Fasting plasma levels of GIP were not affected by EPI; however, the GIP response in EPI and Amylase-treated EPI animals was significantly lower (p < 0.05) when compared to that of the intact, healthy pigs. Orally administered amylase induces gut anti-incretin action, normalizing glucose homeostasis and reducing HOMA-IR as a long-term outcome, thus lowering the risk of diabetes type II development. Amylase has long-lasting anti-incretin effects, and one could consider the existence of a long-lasting gut memory for amylase, which decreases hyperinsulinemia and hyperglycemia for up to 16 h after the last exposure of the gut to amylase.

Designer GLP1 poly-agonist peptides in the management of diabesity

INTRODUCTION

To date, the 21^st Century has witnessed key developments in the management of diabesity (a conflation of obesity and Type 2 Diabetes Mellitus [T2D]), including Glucagon Like Peptide 1 (GLP1) receptor agonist therapies, and recently the 'designer' GLP1 Poly-agonist Peptides (GLP1PPs).

AREAS COVERED

A PubMed search of published data on the GLP1PP class of therapies was conducted. The gut-brain axis forms complex multi-directional interlinks that include autonomic nervous signaling, components of the gut microbiota (including metabolic by-products and gram-negative cell wall components [e.g. endotoxinaemia]), and incretin hormones that are secreted from the gut in response to the ingestion of nutrients. The development of dual-incretin agonist therapies includes combinations of the GLP1 peptide with Glucose-dependent Insulinotropic Polypeptide (GIP), Glucagon (Gcg), Cholecystokinin (CCK), Peptide YY (PYY), and Glucagon-Like Peptide 2 (GLP2). Triple incretin agonist therapies are also under development.

EXPERT OPINION

At the dawn of a new era in the therapeutic management of diabesity, the designer GLP1PP class holds great promise, with each novel combination building on a preexisting palimpsest of clinical data and insights. Future innovations of the GLP1PP class will likely enable medically induced weight loss and glycemic control in diabesity to rival or even out-perform those resulting from bariatric surgery.

Tandem mass tag-based quantitative proteomics analyses of a chicken-original virulent and its attenuated Histomonas meleagridis strain in China

Introduction

Histomonas meleagridis can cause histomonosis in poultry. Due to the prohibition of effective drugs, the prevention and treatment of the disease requires new strategies. Questions about its pathogenic mechanisms and virulence factors remain puzzling.

Methods

To address these issues, a tandem mass tag (TMT) comparative proteomic analysis of a virulent strain and its attenuated strain of Chinese chicken-origin was performed.

Results

A total of 3,494 proteins were identified in the experiment, of which 745 proteins were differentially expressed (fold change ≥1.2 or ≤0.83 and p &lt; 0.05), with 192 up-regulated proteins and 553 down-regulated proteins in the virulent strain relative to the attenuated strain.

Discussion

Surface protein BspA like, digestive cysteine proteinase, actin, and GH family 25 lysozyme were noted among the proteins up regulated in virulent strains, and these several proteins may be directly related to the pathogenic capacity of the histomonad. Ferredoxin, 60S ribosomal protein L6, 40S ribosomal protein S3, and NADP-dependent malic enzyme which associated with biosynthesis and metabolism were also noted, which have the potential to be new drug targets. The up-regulation of alpha-amylase, ras-like protein 1, ras-like protein 2, and involucrin in attenuated strains helps to understand how it is adapted to the long-term in vitro culture environment. The above results provide some candidate protein-coding genes for further functional verification, which will help to understand the molecular mechanism of pathogenicity and attenuation of H. meleagridis more comprehensively.

Genetic factors associated with serum amylase in a Japanese population: combined analysis of copy-number and single-nucleotide variants

Amylase activity and levels in humans are heritable quantitative traits. Although many studies exist on the effects of copy-number variants (CNVs) in amylase genes (AMY) on human phenotypes, such as body mass index (BMI), the genetic factors controlling interindividual variation in amylase levels remain poorly understood. Here, we conducted a genome-wide association study (GWAS) of serum amylase levels (SAL) in 814 Japanese individuals to identify associated single-nucleotide variants (SNVs), after adjusting for non-genetic factors. Diploid copy numbers (CN) of AMY (AMY1, AMY2A, and AMY2B) were measured using droplet digital PCR to examine the association between each diploid CN and SAL. We further assessed the relative contribution of the GWAS-lead SNV and AMY CNVs to SAL. GWAS identified 14 significant SNVs (p < 5 × 10^-8) within a linkage disequilibrium block near the AMY cluster on chromosome 1. The association analyses of AMY CNVs and SAL showed a significant association between AMY1 diploid CN and SAL (p = 1.89 × 10^-19), while no significant association with SAL was found for AMY2A CN (p = 0.54) or AMY2B CN (p = 0.15). In a joint association analysis with SAL using the GWAS-lead SNV and AMY1 diploid CN, AMY1 CN remained significant (p = 5.4 ×10^-13), while the association of the lead SNV was marginal (p = 0.08). We also found no association between AMY1 diploid CN and BMI (p = 0.14). Our results indicate that AMY1 CNV is the major genetic factor for Japanese SAL, with no significant association with BMI.

Prevotella abundance and salivary amylase gene copy number predict fat loss in response to wholegrain diets

Background

Salivary amylase (AMY1) gene copy number (CN) and Prevotella abundance in the gut are involved in carbohydrate digestion in the upper and lower gastrointestinal tract, respectively; and have been suggested as prognostic biomarkers for weight loss among overweight individuals consuming diets rich in fiber and wholegrains.

Objective

We hypothesized that Prevotella abundance would be linked to greater loss of body fat after wholegrain consumption among individuals with low AMY1 CN, but not in those with high AMY1 CN.

Methods

We reanalyzed data from two independent randomized ad libitum wholegrain interventions (fiber intake ∼33 g/d for 6–8 weeks), to investigate the relationship between baseline Prevotella abundance and body fat loss among healthy, overweight participants stratified into two groups by median AMY1 CN. Individuals with no detected Prevotella spp. were excluded from the main analysis.

Results

In both studies, individuals with low AMY1 CN exhibited a positive correlation between baseline Prevotella abundance and fat loss after consuming the wholegrain diet (r > 0.5, P < 0.05), but no correlation among participants with high AMY1 CN (P ≥ 0.6). Following consumption of the refined wheat control diets, there were no associations between baseline Prevotella abundance and changes in body fat in any of the AMY1 groups.

Conclusion

These results suggest that Prevotella abundance together with AMY1 CN can help predict fat loss in response to ad libitum wholegrain diets, highlighting the potential of these biomarkers in personalized obesity management.

The roles of personalized nutrition in obesity and diabetes management: a review

Background & Aims

Nutrition is one of main environmental factor affecting obesity and its related complications such as diabetes and dyslipidemia. Due to growing prevalence of obesity across the world, it seems that nutritional advice alone is not able to combat this health problem. The present overview aimed to summarize the roles of personalized nutrition (PN) in obesity and diabetes management.

Methods

Scopus, PubMed and Google scholar were searched up to February 2021 to find relevant studies with English language in which the roles of PN in obesity and diabetes management were examined.

Results

Recent evidence revealed the importance of gene-environment interactions for management of diabetes mellitus and obesity. Moreover, microbiome research showed that personalized diet based on a combination of clinical and microbial features is likely to improve responses to therapeutic interventions. Epigenetics as well as genetic and environmental factors can also contribute to the treatment. In addition, articles showed significant roles of epigenetics and gut microbiome on providing an individualized diet for obese and diabetic patients.

Conclusion

PN compare to conventional diet can better improve metabolic status in obese and diabetic patients. Considering genetic differences and microbiome patterns along with environmental factors and their interactions are recommended for obesity and diabetes management. This approach can increase success in promoting health and preventing complications related to diabetes and obesity.

Impact of salivary and pancreatic amylase gene copy numbers on diabetes, obesity, and functional profiles of microbiome in Northern Japanese population

Amylase genes reside in a structurally complex locus, and their copy numbers vary greatly, and several studies have reported their association with obesity. The mechanism of this effect was partially explained by changes in the oral and gut microbiome compositions; however, a detailed mechanism has been unclarified. In this study, we showed their association with diabetes in addition to obesity, and further discovered a plausible mechanism of this association based on the function of commensal bacteria. First, we confirmed that the amylase copy number in the population tends to be larger than that reported in other studies and that there is a positive association between obesity and diabetes (p = 1.89E-2 and 8.63E-3). Second, we identified that relative abundance of some genus level microbiome, Capnocytophaga, Dialister, and previously reported bacteria, were significantly associated with amylase copy numbers. Finally, through functional gene-set analysis using shotgun sequencing, we observed that the abundance of genes in the Acarbose pathway in the gut microbiome was significantly decreased with an increase in the amylase copy number (p-value = 5.80E-4). Our findings can partly explain the mechanism underlying obesity and diabetes in populations with high amylase copy numbers.

Diets, nutrients, genes and the microbiome: recent advances in personalised nutrition

As individuals seek increasingly individualised nutrition and lifestyle guidance, numerous apps and nutrition programmes have emerged. However, complex individual variations in dietary behaviours, genotypes, gene expression and composition of the microbiome are increasingly recognised. Advances in digital tools and artificial intelligence can help individuals more easily track nutrient intakes and identify nutritional gaps. However, the influence of these nutrients on health outcomes can vary widely among individuals depending upon life stage, genetics and microbial composition. For example, folate may elicit favourable epigenetic effects on brain development during a critical developmental time window of pregnancy. Genes affecting vitamin B12 metabolism may lead to cardiometabolic traits that play an essential role in the context of obesity. Finally, an individual's gut microbial composition can determine their response to dietary fibre interventions during weight loss. These recent advances in understanding can lead to a more complete and integrated approach to promoting optimal health through personalised nutrition, in clinical practice settings and for individuals in their daily lives. The purpose of this review is to summarise presentations made during the DSM Science and Technology Award Symposium at the 13th European Nutrition Conference, which focused on personalised nutrition and novel technologies for health in the modern world.

Copy number variation: Characteristics, evolutionary and pathological aspects

Copy number variants (CNVs) were the subject of extensive research in the past years. They are common features of the human genome that play an important role in evolution, contribute to population diversity, development of certain diseases, and influence host–microbiome interactions. CNVs have found application in the molecular diagnosis of many diseases and in non-invasive prenatal care, but their full potential is only emerging. CNVs are expected to have a tremendous impact on screening, diagnosis, prognosis, and monitoring of several disorders, including cancer and cardiovascular disease. Here, we comprehensively review basic definitions of the term CNV, outline mechanisms and factors involved in CNV formation, and discuss their evolutionary and pathological aspects. We suggest a need for better defined distinguishing criteria and boundaries between known types of CNVs.

A map of copy number variations in the Tunisian population: a valuable tool for medical genomics in North Africa

Copy number variation (CNV) is considered as the most frequent type of structural variation in the human genome. Some CNVs can act on human phenotype diversity, encompassing rare Mendelian diseases and genomic disorders. The North African populations remain underrepresented in public genetic databases in terms of single-nucleotide variants as well as for larger genomic mutations. In this study, we present the first CNV map for a North African population using the Affymetrix Genome-Wide SNP (single-nucleotide polymorphism) array 6.0 array genotyping intensity data to call CNVs in 102 Tunisian healthy individuals. Two softwares, PennCNV and Birdsuite, were used to call CNVs in order to provide reliable data. Subsequent bioinformatic analyses were performed to explore their features and patterns. The CNV map of the Tunisian population includes 1083 CNVs spanning 61.443 Mb of the genome. The CNV length ranged from 1.017 kb to 2.074 Mb with an average of 56.734 kb. Deletions represent 57.43% of the identified CNVs, while duplications and the mixed loci are less represented. One hundred and three genes disrupted by CNVs are reported to cause 155 Mendelian diseases/phenotypes. Drug response genes were also reported to be affected by CNVs. Data on genes overlapped by deletions and duplications segments and the sequence properties in and around them also provided insights into the functional and health impacts of CNVs. These findings represent valuable clues to genetic diversity and personalized medicine in the Tunisian population as well as in the ethnically similar populations from North Africa.

Association of Serum Amylase Activity and the Copy Number Variation of AMY1/2A/2B with Metabolic Syndrome in Chinese Adults

PURPOSE

Low serum amylase activity and copy number (CN) variation (CNV) of the salivary amylase gene (AMY1) are reportedly associated with obesity and abnormal glucose metabolism; however, this association remains controversial. We aimed to clarify the relationship between serum amylase activity and the CNV of AMY1/2A/2B with the occurrence of metabolic syndrome (MetS) in Chinese adults.

PATIENTS AND METHODS

Anthropometry, metabolic risk factors, and serum amylase activity were assessed in 560 subjects (260 MetS patients; 300 healthy controls). AMY1/2A/2B CNs were evaluated using the highly sensitive droplet digital PCR.

RESULTS

The serum total, pancreatic, and salivary amylase activity, but not the AMY1/2A/2B CNs, was significantly lower in MetS patients than that in the control subjects. Patients <45 y had a lower AMY1 CN, compared to that in healthy controls. Low serum amylase activity was significantly associated with high MetS prevalence (p < 0.001). In the receiver operating characteristic curve analysis, serum amylase activity was a significant diagnostic indicator for MetS. The diagnostic value of total amylase was second only to that of γ-glutamyl transpeptidase; it was higher than that of alanine aminotransferase and uric acid.

CONCLUSION

Low serum amylase activity was significantly associated with increased risk of MetS in Chinese adults. Therefore, amylase could be a potential biomarker for predicting MetS.

Factors contributing to stability and instability in alpha-amylase activity in diluted saliva samples over time

For the measurement of salivary alpha-amylase (sAA) activity, saliva samples first have to be diluted. There is some evidence for instability, that is, a decline of sAA activity in diluted samples. It is not clear which factors during dilution may contribute to this phenomenon and how quickly this decline of sAA activity occurs. Several experiments were conducted to investigate whether and how the material of the container (polystyrene (PS), polypropylene (PP), glass; experiment 1) and the diluent (saline (NaCl) solution, phosphate buffer saline (PBS), ultra-pure water; experiment 2) may affect sAA stability in diluted samples over a broad time window of up to 5 h. To study the velocity of the phenomenon in a fine-grained temporal resolution, sAA activity during the dilution process was studied (experiment 3). The results suggest that the (in)stability of sAA activity in diluted samples is determined by the interaction of material, diluent, and time. The sAA activity was relatively stable if saliva samples were diluted with a NaCl solution or PBS in glass tubes. However, sAA activity in diluted samples decreased in plastic containers (PS, PP), or if ultra-pure water was used as the diluent. There was a clear time effect on this decline. However, the decline appears to require some time to evolve and may not occur immediately during the dilution process. To conclude, the dilution of saliva samples should preferably be conducted with NaCl solution or PBS in glass containers. If glass containers are not available, PS and PP containers can be used if the dilution is processed quickly (within 25 min) and the measurement is initiated immediately upon dilution.

AMY1 Gene Copy Number Correlates With Glucose Absorption and Visceral Fat Volume, but Not with Insulin Resistance

BACKGROUND

The human amylase gene (AMY1) has a broad copy number (CN) variation that may associate with body mass index.

METHODS

Deoxyribonucleic acid was extracted from urine (n = 74) and serum (n = 6) samples (Protein, Fiber and Metabolic Syndrome [ProFiMet] cohort), and buccal (n = 17) samples (Oral Starch Challenge [OSC] cohort), and assessed for AMY1 CN by droplet digital polymerase chain reaction. The association of AMY1 CN with comprehensive markers of metabolic status (ProFiMet cohort) were analyzed with Pearson's correlation coefficient (CC). For the healthy, euglycemic OSC cohort, glycemic response to OSC was analyzed with independent sample t-tests (subgroups: high AMY1 CN 9-12, n = 10; low AMY1 CN 4-6, n = 7).

RESULTS

There were significant inverse correlations of AMY1 CN with total visceral fat volume (CC -0.33; P = 0.004) and positive correlations of AMY1 CN with oral glucose insulin sensitivity score (derived from an oral glucose tolerance test, CC 0.26; P = 0.02), serum HDL-cholesterol (CC 0.325; P = 0.003), and serum adiponectin (CC 0.249; P = 0.026). Linear regression multivariate analysis (adiponectin as dependent variable), showed independent association of adiponectin with AMY1 CN (Beta = 0.29; P = 0.03). There were no significant associations between AMY1 CN and clamp-derived M-value, homeostasis model assessment of insulin resistance (IR), hepatic endogenous glucose production, fecal floral signature, or macronutrient dietary preference. Delta (mean) change in blood glucose concentration (fasting to 30-minutes post-OSC) was significantly greater in the high versus low AMY1 CN subgroups (mean 1.7 mmol/l [SEM 0.6] vs 0.9 mmol/l [SEM 0.9], respectively; P = 0.016).

CONCLUSIONS

High AMY1 CN associates with a favorable metabolic profile (lower visceral fat volume, higher serum adiponectin, enhanced glucose absorption following oral glucose, and OSC), but not with whole-body or hepatic IR.

Time Course of Salivary Protein Responses to Cranberry-Derived Polyphenol Exposure as a Function of PROP Taster Status

Astringency is a complex oral sensation, commonly experienced when dietary polyphenols interact with salivary proteins. Most astringent stimuli alter protein levels, which then require time to be replenished. Although it is standard practice in astringency research to provide breaks in between stimuli, there is limited consensus over the amount of time needed to restore the oral environment to baseline levels. Here we examined salivary protein levels after exposure to 20 mL of a model stimulus (cranberry polyphenol extract, 0.75 g/L CPE) or unsweetened cranberry juice (CJ), over a 10 min period. Whole saliva from healthy subjects (n = 60) was collected at baseline and after 5 and 10 min following either stimulus. Five families of proteins: basic proline-rich proteins (bPRPs); acidic proline-rich proteins (aPRPs); histatins; statherin; and S-type cystatins, were analyzed in whole saliva via HPLC-low resolution-ESI-IT-MS, using the area of the extracted ion current (XIC) peaks. Amylase was quantified via immunoblotting. In comparison to baseline (resting), both stimuli led to a rise in levels of aPRPs (p < 0.000) at 5 min which remained elevated at 10 min after stimulation. Additionally, an interaction of PROP taster status and time was observed, wherein super-tasters had higher levels of amylase in comparison to non-tasters after stimulation with CJ at both timepoints (p = 0.014–0.000). Further, male super-tasters had higher levels of bPRPs at 5 min after stimulation with both CJ and CPE (p = 0.015–0.007) in comparison to baseline. These data provide novel findings of interindividual differences in the salivary proteome that may influence the development of astringency and that help inform the design of sensory experiments of astringency.

Pretreatment Prevotella-to-Bacteroides ratio and salivary amylase gene copy number as prognostic markers for dietary weight loss

BACKGROUND

The inconsistent link observed between salivary amylase gene copy number (AMY1 CN) and weight management is likely modified by diet and microbiome.

OBJECTIVE

Based on analysis of a previously published study, we investigated the hypothesis that interaction between diet, Prevotella-to-Bacteriodes ratio (P/B ratio), and AMY1 CN influence weight change.

METHODS

Sixty-two people with increased waist circumference were randomly assigned to receive an ad libitum New Nordic Diet (NND) high in dietary fiber, whole grain, intrinsic sugars, and starch or an Average Danish (Western) Diet (ADD) for 26 weeks. All foods were provided free of charge. Before subjects were randomly assigned to receive the NND or ADD diet, blood and fecal samples were collected, from which AMY1 CN and P/B ratio, respectively, were determined. Body weight change was described by using linear mixed models, including biomarker [log10(P/B ratio) and/or AMY1 CN] diet-group interactions.

RESULTS

Baseline means ± SDs of log10(P/B ratio) and AMY1 CN were -2.1 ± 1.8 and 6.6 ± 2.4, respectively. Baseline P/B ratio predicted a 0.99-kg/unit (95% CI: 0.40, 1.57; n = 54; P < 0.001) higher weight loss for those subjects on the NND compared with those on the ADD diet, whereas AMY1 CN was not found to predict weight loss differences between the NND and ADD groups [0.05 kg/CN (95% CI: -0.40, 0.51; n = 54; P = 0.83)]. However, among subjects with low AMY1 CN (<6.5 copies), baseline P/B ratio predicted a 2.12-kg/unit (95% CI: 1.37, 2.88; n = 30; P < 0.001) higher weight loss for the NND group than the ADD group. No such differences in weight loss were found among subjects in both groups with high AMY1 CN [-0.17 kg/unit (95% CI: -1.01, 0.66; n = 24; P = 0.68)].

CONCLUSIONS

The combined use of low AMY1 CN and pretreatment P/B ratio for weight loss prediction led to highly individualized weight loss results with the introduction of more fiber, whole grain, intrinsic sugars, and starch in the diet. These preliminary observations suggest that more undigested starch reaches the colon in individuals with low AMY1 CN, and that the fate of this starch depends on the gut microbiota composition. This trial was registered at clinicaltrials.gov as NCT01195610.

Decreased basal and stimulated salivary parameters by histopathological lesions and secretory dysfunction of parotid and submandibular glands in rats with type 2 diabetes

Patients with type 2 diabetes mellitus (T2DM) present with dry mouth, polydipsia and taste impairment due to salivary secretion disorder. However, the underlying functional mechanism of T2DM remains unknown. The present study found that T2DM rats had significantly lower salivary flow rate and salivary alpha amylase activity, and attenuated salivary secretion responses to acid stimulation compared with control rats. Histopathological observation found that T2DM rats had inflammatory cell infiltration with increased expressions of IL-6 and TNF-α, oxidative stress, including decreased total superoxide dismutase activity and increased malondialdehyde content, and decreased expressions of β1 adrenergic receptor, cholinergic receptor, aquaporin-5 and protein kinase A in salivary glands, in particular the parotid gland. These results indicated that parotid gland impairment was more severe compared with submandibular gland impairment. Reduced salivary secretion may be associated with histopathological lesions and decreased regulation in secretory pathways in salivary glands.

Copy Number Variation of the Salivary Amylase Gene and Glucose Metabolism in Healthy Young Japanese Women

Background

Many studies have shown that low copy number variation (CNV) of the salivary amylase gene (AMY1) and low serum amylase concentration are associated with impaired glucose metabolism and obesity. We aimed to clarify the conflicting results of previous studies by examining AMY1 expression and metabolic indices in a homogenous group of healthy participants.

Methods

Sixty healthy non-obese young Japanese women aged 20 - 39 years were examined for AMY1 CNV, salivary amylase, body mass index (BMI) and serum parameters including glycated hemoglobin (HbA1c), ketones, and total, salivary and pancreatic amylase. Respiratory quotient at rest and changes in blood glucose after starch loading were also examined.

Results

AMY1 CNV (range, 4 - 14) and the level of serum salivary amylase were correlated inversely with HbA1c (r = -0.36, P = 0.003 and r = -0.30, P = 0.02, respectively), whereas the percentage of serum salivary amylase in total serum amylase was positively correlated with blood glucose at 30 and 45 min after starch loading (r = 0.38, P = 0.004 and r = 0.27, P = 0.04, respectively). The level of serum total amylase, but not AMY1 CNV, was correlated inversely with BMI (r = -0.29, P = 0.02). Logistic regression analysis showed that low AMY1 CNV (4 - 7) was significantly associated with an HbA1c of ≥ 5.4% (34 mmol/mol) even after adjustment for age, BMI and energy consumption, compared with high AMY1 CNV (8 - 14).

Conclusions

Although a higher percentage of serum salivary amylase was associated with higher levels of blood glucose at the early stage after starch loading, low AMY1 CNV was associated with chronic unfavorable glucose metabolism in healthy non-obese young women in Japan.

Prevotella Abundance Predicts Weight Loss Success in Healthy, Overweight Adults Consuming a Whole-Grain Diet Ad Libitum: A Post Hoc Analysis of a 6-Wk Randomized Controlled Trial

BACKGROUND

The key to effective weight loss may be to match diet and gut microbes, since recent studies have found that subjects with high Prevotella abundances in their gut microbiota lose more weight on diets rich in fiber than subjects with low Prevotella abundances.

OBJECTIVES

We reanalyzed a 6-wk, parallel, randomized trial to investigate difference in body weight changes when participants, stratified by fecal microbiota composition, consumed ad libitum a whole-grain (WG) or a refined-wheat (RW) diet.

METHODS

We stratified 46 (19 men, 27 women; ages 30-65 y) healthy, overweight adults by baseline Prevotella-to-Bacteroides ratios and Prevotella abundances. Subjects with no Prevotella were analyzed separately (n = 24). Compared with the RW diet (mean = 221 g/d), the WG diet (mean = 228 g/d) had a higher fiber content (33 g/d compared with 23 g/d). Linear mixed models and correlations were applied to link 6-wk changes in body weights and metabolic and microbiota markers, according to Prevotella groups and diets.

RESULTS

The Prevotella abundances correlated inversely with weight changes (r = -0.34; P = 0.043). Consequently, subjects with high Prevotella abundances (n = 15) spontaneously lost 1.80 kg (95% CI: -3.23, -0.37 kg; P = 0.013) more on the WG diet than on the RW diet, whereas those with low Prevotella abundances (n = 31) were weight stable (-0.22 kg; 95% CI: -1.40, 0.96 kg; P = 0.72). Thus, the mean difference between the Prevotella groups was 2.02 kg (95% CI: -3.87, -0.17 kg; P = 0.032). Subjects with no Prevotella lost 1.59 kg (95% CI: -2.65, -0.52 kg; P = 0.004) more on the WG diet than on the RW diet. No 6-wk changes in appetite sensations, glucose metabolisms, or fecal SCFAs were associated with the Prevotella groups.

CONCLUSIONS

Healthy, overweight adults with high Prevotella abundances lost more weight than subjects with low Prevotella abundances when consuming a diet rich in WG and fiber ad libitum for 6 wk. This further supports enterotypes as a potential biomarker in personalized nutrition for obesity management. This t rial was registered at clinicaltrials.gov as NCT02358122.