Repetitive pain experiences modulate feedforward control of hemodynamics and modification by nitrous oxide/oxygen inhalation in humans.

Background: Repetitive experiences of certain stresses evoke feedforward cardiovascular responses via central command (CC)--central signals from the higher brain. However, it is unclear whether the anticipatory cardiovascular responses before pain stimulation occur after repetitive pain experiences and how nitrous oxide/oxygen inhalation (N2O), a sedative widely used in dentistry, affects the responses. We tested the hypothesis that the repetitive cold pressor test (CPT) alters the anticipatory cardiovascular responses, which are attenuated by N2O. Materials and methods: Beat-to-beat systolic (SBP) and diastolic blood pressure (DBP), heart rate (HR), and finger arterial stiffness (ß-stiffness) were measured during the 5-min rest, 30-s countdown (CD) before CPT, 2-min CPT, and 3-min recovery (CPT[1st]) in 15 young adults [age, 28 ± 4 years]. The same protocols were repeated randomly with the second CPT (CPT + CC) or placebo test (PLCB + CC). Results: SBP and DBP increased from baseline in CPT[1st] and CPT + CC under room air (RA) and 40 % N2O, while SBP was lower under N2O than under RA in CPT[1st]. HR in CPT[1st] was lower under N2O than under RA. The change (Δ) in HR was smaller during CPT[1st] than during CPT + CC under N2O, and a similar trend was observed under RA. ΔSBP by CD was lower under N2O than under RA in CPT[1st] but not in CPT + CC. HR increased with CD in CPT + CC but not in CPT[1st] under both RA and N2O. ß-stiffness increased by CD regardless of the pain experience, while it was lower under N2O. Conclusion: Repetitive pain experiences induce a feedforward HR increase. 40 % N2O decreases vascular stiffness, which may attenuate the anticipatory pressor response only when the feedforward HR increase does not exist.

Palatal microbiota associated with membranous substances in older Japanese individuals undergoing tube feeding in long-term care: A cross-sectional study.

Objective: Tube feeders are prone to membranous substance formation on the palate, and those with membranous substances have a risk of fever, with the probable involvement of their oral bacteria. However, the palatal microbiota of those with membranous substances has not been elucidated. Therefore, we evaluated the differences in palatal microbiota between tube-fed individuals with and without membranous substances to clarify the microbiota. Materials and methods: This study included 19 participants aged 65 years who required tube feeding. The participants' characteristics were collected from nursing records and oral examinations. If membranous materials were found on the palate, a specimen was collected. Membranous substances were defined as keratotic degeneration observed under a microscope. Additionally, we performed a comprehensive microbiome analysis by extracting DNA from the samples and performing 16 S rRNA gene sequencing. Finally, we compared the participant demographics and oral microbiota between patients with and without membranous substances. Results: A total of 11 participants had membranous substances associated with "mouth dryness" (p < 0.001) and "constant mouth opening" (p = 0.020). Palatal microbiota differed between those with and without membranous substances. Among the bacteria with a relative abundance greater than 1.0%, the abundance of Streptococcus (p = 0.007), Fusobacterium (p = 0.041), Streptococcus agalactiae (p = 0.009), and Fusobacterium nucleatum subsp. vincentii (p = 0.026) was significantly higher in the membranous substance group than in the non-membranous substance group. Conclusions: The palatal microbiota of individuals undergoing tube feeding differed depending on the presence or absence of membranous substances. Membrane substance formation associated with dry mouth purportedly alters the palatal microbiota. Streptococcus, Fusobacterium, S. agalactiae, and F. nucleatum subsp. vincentii were more abundant in the oral microbiota of patients with membranous substances. Thus, preventing this formation may help in controlling the growth of these microbes.

Pharyngeal Deposits Comprising Salivary Mucin in Tube-fed Elderly Patients: MUC2 and MUC7 Immunoreactivity.

Several investigators have reported that oral membranous and pharyngeal viscous deposits developed in bedridden elderly persons requiring nursing care without oral intake. Therefore, this study aimed to clarify the origin of viscous deposits on the pharyngeal mucosa based on characteristics of salivary and tracheal secretory mucin. The participants were 35 elderly people who required nursing care. All 46 collected specimens, including 30 intraoral and 16 pharyngeal specimens, were stained against specific mucins secreted from the respiratory tract and saliva gland using antibodies anti-MUC2 and anti-MUC7, respectively. Out of 35 participants, the intraoral membranous deposits and deposits on the pharyngeal mucosa developed in 17 (48.6%) and 10 persons (28.6%), respectively. The pharyngeal deposits developed in 58.8% of participants who developed intraoral deposits. All pathological specimens shared microscopic findings of various combinations of eosinophilic lamellar structure and a pale-basophilic amorphous substance. Immunohistochemically, both the 30 oral and the 16 pharyngeal specimens obtained from 17 participants were consistently positive for MUC7 but negative for MUC2. In conclusion, we clarified that the mucoid component of both oral and pharyngeal deposits comprised MUC7 salivary mucin, which revealed that both deposits originated from the oral cavity. This result strongly suggests that oral care is intimately related to oral and pharyngeal conditions.

Histopathological evaluation of oral membranous substance in bedridden elderly persons without oral intake in Japan.

OBJECTIVES: The aim of this study was to clarify by histopathological examination the origin of oral membranous substances deposited on the palate, tongue, buccal mucosa and teeth. BACKGROUND: Several investigators have reported membranous substances deposited in the mouths of bedridden elderly persons requiring nursing care without oral intake. However, the precise nature and origin of the substances are poorly understood. METHODS: Sixty-nine specimens were taken from the oral cavity of bedridden patients, that is, the palate, dorsum of the tongue, the cheek and teeth. Sections were stained with haematoxylin and eosin stain, alcian-blue and periodic acid-Schiff stain (AB-PAS) and antibodies for pankeratin (AE1AE3) and leukocyte common antigen (LCA). RESULTS: All specimens showed a film-like nature coloured from tan to white, accompanied by a mucous substance. Histologically, specimens of all sites had a similar feature of the combination of basophilic amorphous and eosinophilic lamellar features. The basophilic substance was positive for AB-PAS, and PAS-positive glycogen granules were also noted in the lamellar structure. Immunochemistry revealed various degrees of pankeratin positive substance and LCA-positive inflammatory cell infiltration. CONCLUSION: The oral membranous substance was composed of keratin and mucin with inflammation. These results suggest that the deposition of the oral membranous substance is a pathological condition or oral mucositis caused by dry mouth.