Enhancement of Gustatory Neural Responses by Parasympathetic Nerve in the Frog.

The autonomic nervous system affects the gustatory responses in animals. Frog glossopharyngeal nerve (GPN) contains the parasympathetic nerve. We checked the effects of electrical stimulation (ES) of the parasympathetic nerves on the gustatory neural responses. The gustatory neural impulses of the GPNs were recorded using bipolar AgCl wires under normal blood circulation and integrated with a time constant of 1 s. Electrical stimuli were applied to the proximal side of the GPN with a pair of AgCl wires. The parasympathetic nerves of the GPN were strongly stimulated for 10 s with 6 V at 30 Hz before taste stimulation. The integrated neural responses to 0.5 M NaCl, 2.5 mM CaCl2, water, and 1 M sucrose were enhanced to 130-140% of the controls. On the other hand, the responses for 1 mM Q-HCl and 0.3 mM acetic acid were not changed by the preceding applied ES. After hexamethonium (a blocker of nicotinic ACh receptor) was intravenously injected, ES of the parasympathetic nerve did not modulate the responses for all six taste stimuli. The mechanism for enhancement of the gustatory neural responses is discussed.

Investigation of vacuum forming techniques for reduction of loss in mouthguard thickness: part 2­effects of sheet grooving and thermal shrinkage.

The aim of this study was to investigate vacuum forming techniques for reduction of loss in mouthguard thickness effects of sheet grooving and thermal shrinkage of extruded sheets on molded mouthguard thickness. Mouthguards were fabricated with ethylene vinyl acetate (EVA) sheets (4.0 mm thick) using a vacuum forming machine. Sheet form was a convexing v-shaped groove toward the back, 10-40 mm from the anterior end. The sheets were placed in the forming machine with the sheet extrusion direction either vertical or parallel to the model's centerline of right and left. Molding was performed by crimping the sheet using suction when the most descending portion of the sheet sagged downwards from the clamp, 15 mm below the basal surface. Postmolding thickness was determined using a measuring device. Measurement points were the incisal portion (incisal edge and labial surface) and molar portion (cusp and buccal surface). Differences in molded mouthguard thickness with the sheet orientation of extruded EVA sheets were analyzed by student's t-test. The sheet in parallel axis orientation with the model's centerline yielded higher thickness than vertical orientation at the labial surface and the buccal surface. The present results suggested that addition of a groove to the sheet in conjunction with placement of the sheet with its axis of orientation parallel the centerline of the working model can effectively reduce thickness loss in the molded mouthguard with the equipment and materials used in this study.

Ingestion of hyaluronans (molecular weights 800 k and 300 k) improves dry skin conditions: a randomized, double blind, controlled study.

Hyaluronan (HA) has been increasingly used as a dietary supplement to improve the skin. However, the effect of ingested HA may depend on its molecular weight (MW) because its physiological activities in the body vary with its MW. In this study, we examined the effects of ingested HA with varying MW on the skin. In this randomized, double blind, placebo controlled study, 61 subjects with dry skin received oral HA (120 mg/day), of MWs 800 k and 300 k or placebo, for 6 weeks. The skin moisture contents of the first two groups increased more than those of the placebo group during the ingestion period. In addition, group HA 300 k exhibited significant improvements in skin moisture content 2 weeks after ingestion ended compared with the placebo group. A questionnaire survey about subjective facial aging symptoms showed that the HA treated groups exhibited significantly improved the skin condition compared with the placebo treated group. Furthermore, dermatologists objectively evaluated the clinical symptoms of the facial and whole body skin, showing that no adverse events were related to daily ingestion of HA. This study shows that both of ingesting HAs (MWs 800 k and 300 k) improved the skin condition by increasing the moisture content.

Ingested hyaluronan moisturizes dry skin.

Hyaluronan (HA) is present in many tissues of the body and is essential to maintain moistness in the skin tissues, which contain approximately half the body's HA mass. Due to its viscosity and moisturizing effect, HA is widely distributed as a medicine, cosmetic, food, and, recently marketed in Japan as a popular dietary supplement to promote skin moisture. In a randomized, double-blind, placebo-controlled clinical study it was found that ingested HA increased skin moisture and improved treatment outcomes for patients with dry skin. HA is also reported to be absorbed by the body distributed, in part, to the skin. Ingested HA contributes to the increased synthesis of HA and promotes cell proliferation in fibroblasts. These effects show that ingestion of HA moisturizes the skin and is expected to improve the quality of life for people who suffer from dry skin. This review examines the moisturizing effects of dry skin by ingested HA and summarizes the series of mechanisms from absorption to pharmacological action.

Efferent fibers innervate gustatory and mechanosensitive afferent fibers in frog fungiform papillae.

A possibility of efferent innervation of gustatory and mechanosensitive afferent fiber endings was studied in frog fungiform papillae with a suction electrode. The amplitude of antidromic impulses in a papillary afferent fiber induced by antidromically stimulating an afferent fiber of glossopharyngeal nerve (GPN) with low voltage pulses was inhibited for 40 s after the parasympathetic efferent fibers of GPN were stimulated orthodromically with high voltage pulses at 30 Hz for 10 s. This implies that electrical positivity of the outer surface of papillary afferent membrane was reduced by the efferent fiber-induced excitatory postsynaptic potential. The inhibition of afferent responses in the papillae was blocked by substance P receptor blocker, L-703,606, indicating that substance P is probably released from the efferent fiber terminals. Slow negative synaptic potential, which corresponded to a slow depolarizing synaptic potential, was extracellularly induced in papillary afferent terminals for 45 s by stimulating the parasympathetic efferent fibers of GPN with high voltage pulses at 30 Hz for 10 s. This synaptic potential was also blocked by L-703,606. These data indicate that papillary afferent fiber endings are innervated by parasympathetic efferent fibers.

Oral administration of polymer hyaluronic acid alleviates symptoms of knee osteoarthritis: a double-blind, placebo-controlled study over a 12-month period.

This study was conducted to investigate the efficacy of oral hyaluronic acid (HA) administration for osteoarthritis (OA) in knee joints. Sixty osteoarthritic subjects (Kellgren-Lawrence grade 2 or 3) were randomly assigned to the HA or placebo group. The subjects in the HA group were given 200 mg of HA once a day everyday for 12 months, while the subjects in the placebo group were given placebo. The subjects in both groups were requested to conduct quadriceps strengthening exercise everyday as part of the treatment. The subjects' symptoms were evaluated by the Japanese Knee Osteoarthritis Measure (JKOM) score. The symptoms of the subjects as determined by the JKOM score improved with time in both the HA and placebo groups. This improvement tended to be more obvious with the HA group, and this trend was more obvious with the subjects aged 70 years or less. For these relatively younger subjects, the JKOM score was significantly better than the one for the placebo group at the 2nd and 4th months after the initiation of administration. Oral administration of HA may improve the symptoms of knee OA in patients aged 70 years or younger when combined with the quadriceps strengthening exercise.

Effect of Antimicrobial Prophylaxis Duration on Health Care-Associated Infections After Clean Orthopedic Surgery: A Cluster Randomized Trial.

Importance: Postoperative health care-associated infections are associated with a greater deterioration in patients' general health status and social and economic burden, with at least 1 occurring in approximately 4% of acute care hospital patients. Antimicrobial prophylaxis prevents surgical site infections in various orthopedic procedures; however, its relationship with health care-associated infections remains unknown. Objective: To examine whether a shorter antimicrobial prophylaxis duration of less than 24 hours after surgery is not inferior to a longer duration in preventing health care-associated infections after clean orthopedic surgery. Design, Setting, and Participants: This open-label, multicenter, cluster randomized, noninferiority clinical trial was conducted in 5 tertiary referral hospitals in greater Tokyo metropolitan area, Japan, from May to December 2018. Adult patients undergoing clean orthopedic surgery were recruited until the planned number of participants was achieved (500 participants per group). Statistical analysis was conducted from July to December 2019. Interventions: Antimicrobial prophylaxis was discontinued within 24 hours after surgery in group 24 and 24 to 48 hours after surgery in group 48. Group allocation was switched every 2 or 4 months according to the facility-based cluster rule. Study-group assignments were masked from participants. Main Outcomes and Measures: The primary outcome was the incidence of health care-associated infections requiring antibiotic therapies within 30 days after surgery. The noninferiority margin was 4%. Results: Of the 1211 participants who underwent cluster allocation, 633 participants were in group 24 (median [IQR] age, 73 [61-80] years; 250 men [39.5%] and 383 women [60.5%]), 578 participants were in group 48 (median [IQR] age, 74 [62-81] years; 204 men [35.3%] and 374 women [64.7%]), and all were eligible for the intention-to-treat analyses. Health care-associated infections occurred in 29 patients (4.6%) in group 24 and 38 patients (6.6%) in group 48. Intention-to-treat analyses showed a risk difference of -1.99 percentage points (95% CI, -5.05 to 1.06 percentage points; P < .001 for noninferiority) between groups, indicating noninferiority. Results of adjusted intention-to-treat, per-protocol, and per designated procedure population analyses supported this result, without a risk of antibiotic resistance and prolonged hospitalization. Conclusions and Relevance: This cluster randomized trial found noninferiority of a shorter antimicrobial prophylaxis duration in preventing health care-associated infections without an increase in antibiotic resistance risk. These findings lend support to the global movement against antimicrobial resistance and provide additional information on adequate antimicrobial prophylaxis for clean orthopedic surgery. Trial Registration: Identifier: UMIN000030929.

The receptor potential of frog taste cells in response to cold and warm stimuli.

Temperature sensitivity of frog taste cells was studied. The taste cell designated Type thermosensitive (TS) I cell was depolarized by warm stimulus at 30 degrees C and hyperpolarized by cold stimulus at 10 degrees C. The taste cell designated Type TS II cell was depolarized by the cold stimulus and hyperpolarized by the warm stimulus. Menthol solution at 20 degrees C, which selectively activates transient receptor potential (TRP) M8 channels sensitive to cold stimuli, depolarized Type TS II cells but not Types TS I cells. Thermal stimuli-induced receptor potentials were all blocked by a nonselective cation channel blocker flufenamic acid. The results indicate that Type TS I cells have warm sensor channels alone, Type TS II cells have cold sensor channels alone and both the channels are a nonselective cation channel. The candidate of cold sensor channel in Type TS II cells is a TRPM8 channel and that of warm sensor channel in Type TS I cells is likely to be a TRPM4-like channel from the published data. In a subset of taste cells, Types TS III and TS IV cells were found. The former was depolarized by both cold and warm stimuli, but the latter was hyperpolarized by both stimuli. Types TS III and TS IV cells might have both TRPM4-like and TRPM8 channels. It is supposed that depolarizations induced by both cold and warm stimuli were dominant in Type TS III cells and hyperpolarizations induced by both the thermal stimuli were dominant in Type TS IV cells.

Relationships between the upper central incisor crown forms and degree of labial inclination, overbite, and overjet in Japanese young adults.

PURPOSE: The present study aimed to investigate the relationships between the crown form of the upper central incisor and their labial inclination, overbite, and overjet. MATERIALS AND METHODS: Maxillary and mandibular casts of 169 healthy dentitions were subjected to 3D dental scanning, and analyzed using CAD software. The crown forms were divided into tapered, square, and ovoid based on the mesiodistal dimensions at 20% of the crown height to that at 40%. The degree of labial inclination of the upper central incisor was defined as the angle between the occlusal plane and the line connecting the incisal edge and tooth cervix. The incisal edges of the right upper and lower central incisor that in contact with lines parallel to the occlusal plane were used to determine the overbite and overjet. One-way ANOVA was performed to compare the labial inclination, overbite, and overjet among the crown forms. RESULTS: The crown forms were classified into three types; crown forms with a 20%/40% dimension ratio of 1.00±0.01 were defined as square, >1.01 as tapered, and <0.99 as ovoid. The labial inclination degree was the greatest in tapered and the least in square. Both overbite and overjet in tapered and ovoid were higher than those in square. CONCLUSION: Upper central incisor crown forms were related to their labial inclination, overbite, and overjet. It was suggested that the labial inclination, overbite, and overjet should be taken into consideration for the prosthetic treatment or restoring the front teeth crowns.

Effect of gap junction blocker beta-glycyrrhetinic acid on taste disk cells in frog.

A gap junction blocker, 18beta-glycyrrhetinic acid (beta-GA), increased the membrane resistance of Ia, Ib and II/III cells of frog taste disk by 50, 160, and 300 M Omega, respectively, by blocking the gap junction channels and hemichannels. The amplitudes of gustatory depolarizing potentials in the disk cells for 4 basic taste stimuli were reduced to 40-60% after intravenous injection of beta-GA at 1.0 mg/kg. beta-GA of 1.0 mg/kg did not affect the resting potentials and the reversal potentials for tastant-induced depolarizing potentials in any taste disk cells. The percentage of cells responding to each of 4 basic taste stimuli and varying numbers of 4 taste qualities did not differ between control and beta-GA-treated taste disk cells. This implies that gustatory depolarizing response profiles for 4 basic taste stimuli were very similar in control and beta-GA-treated taste disk cells. It is concluded that beta-GA at 1.0 mg/kg reduced the amplitude of gustatory depolarizing potentials in taste disk cells by strongly blocking depolarizing currents flowing through the gap junction channels and hemichannels, but probably weakly affected the gustatory transduction mechanisms for 4 taste stimuli.

Interaction between gustatory depolarizing receptor potential and efferent-induced slow depolarizing synaptic potential in frog taste cell.

Electrical stimulation of parasympathetic nerve (PSN) efferent fibers in the glossopharyngeal nerve induced a slow depolarizing synaptic potential (DSP) in frog taste cells under hypoxia. The objective of this study is to examine the interaction between a gustatory depolarizing receptor potential (GDRP) and a slow DSP. The amplitude of slow DSP added to a tastant-induced GDRP of 10 mV was suppressed to 60% of control slow DSPs for NaCl and acetic acid stimulations, but to 20-30% for quinine-HCl (Q-HCl) and sucrose stimulations. On the other hand, when a GDRP was induced during a prolonged slow DSP, the amplitude of GDRPs induced by 1 M NaCl and 1 M sucrose was suppressed to 50% of controls, but that by 1 mM acetic acid and 10 mM Q-HCl unchanged. It is concluded that the interaction between GDRPs and efferent-induced slow DSPs in frog taste cells under hypoxia derives from the crosstalk between a gustatory receptor current across the receptive membrane and a slow depolarizing synaptic current across the proximal subsynaptic membrane of taste cells.

Electrical properties and gustatory responses of various taste disk cells of frog fungiform papillae.

We compared the electrical properties and gustatory response profiles of types Ia cell (mucus cell), Ib cell (wing cell), and II/III cell (receptor cell) in the taste disks of the frog fungiform papillae. The large depolarizing responses of all types of cell induced by 1 M NaCl were accompanied by a large decrease in the membrane resistance and had the same reversal potential of approximately +5 mV. The large depolarizing responses of all cell types for 1 mM acetic acid were accompanied by a small decrease in the membrane resistance. The small depolarizing responses of all cell types for 10 mM quinine-HCl (Q-HCl) were accompanied by an increase in the membrane resistance, but those for 1 M sucrose were accompanied by a decrease in the membrane resistance. The reversal potential of sucrose responses in all cell types were approximately +12 mV. Taken together, depolarizing responses of Ia, Ib, and II/III cells for each taste stimulus are likely to be generated by the same mechanisms. Gustatory depolarizing response profiles indicated that 1) each of Ia, Ib, and II/III cells responded 100% to 1 M NaCl and 1 mM acetic acid with depolarizing responses, 2) approximately 50% of each cell type responded to 10 mM Q-HCl with depolarizations, and 3) each approximately 40% of Ia and Ib cells and approximately 90% of II/III cells responded to 1 M sucrose with depolarizations. These results suggest that the receptor molecules for NaCl, acid, and Q-HCl stimuli are equivalently distributed on all cell types, but the receptor molecules for sugar stimuli are richer on II/III cells than on Ia and Ib cells. Type III cells having afferent synapses may play a main role in gustatory transduction and transmission.

Highly producible method for determination of occlusal vertical dimension: relationship between measurement of lip contact position with the closed mouth and area of upper prolabium.

PURPOSE: A new method inducing the physiologic rest position of the mandible using the lip contact position with the closed mouth have compared with those obtained using conventional methods of placing the mandible in the physiologic rest position. METHODS: The lip contact position with the closed mouth as a method was investigated whether the technique was useful for determining the occlusal vertical dimension. The relationship between the space between the maxillary and mandibular front teeth in the lip contact position with the closed mouth and the areas of the prolabia was also investigated. RESULTS: Median space between the maxillary and mandibular front teeth in the lip contact position with the closed mouth was 1.53mm, a value intermediate between the value of 2.16mm in the resting mandibular position obtained by the conventional technique and that of 1.33mm in the swallowing position. The coefficient of variation of the space in the lip contact position with the closed mouth was significantly lower than those in the resting mandibular position and in the swallowing position. A significant positive correlation was recognized between the space in the lip contact position with the closed mouth and the area of the prolabium of the upper lip. CONCLUSIONS: These results clarified that the lip contact position with the closed mouth obtained the excellent reproducibility comparing to the conventional methods. These findings suggested that the area of the prolabium of the upper lip might offer an effective index for individual determination of the correct free-way space.

[Effect of differences in guide plane configuration on abutment tooth displacement during clasp insertion].

PURPOSE: Three types of guide plane were compared to clarify the effect of guide plane setting conditions on abutment displacement which arises when an Akers clasp is inserted. METHODS: An experimental model with an artificial periodontal membrane made of hydrophilic vinyl polysiloxane impression material was created. Abutments given a guide plane with only a clasp body (G1), a guide plane whose span extended as far as the reciprocal clasp arm shoulder region diametrically opposite the retention area (G2), and a guide plane for the entire reciprocal clasp arm region (G3) were created, and an Akers clasp was made for each abutment. The amount of abutment displacement and the degree of rotation that arose in the abutment when the Akers clasp was inserted were detected with three laser displacement sensors for comparison. RESULTS: The amount of abutment displacement that arose when the clasp was inserted was higher with G1 than with G2 and G3 in the lingual and distal directions, and no difference was seen between G2 and G3. It was lower with G1 than with G2 and G3 in the buccal direction, and no difference was seen between G2 and G3. It was high with G1 in the mesial direction, and the abutment rotation was high, whereas they were low in the case of G3. A difference was seen between each condition. CONCLUSIONS: Differences in guide plane setting conditions affected the abutment displacement that arose when an Akers clasp was inserted, suggesting that a difference in reciprocal action is seen depending on the setting conditions of the guide plane.

Relationship between cardiac output and mixed venous-arterialPCO 2 gradient in sodium bicarbonate-treated dogs.

We examined the relationship between cardiac output (CO) and mixed venous-arterialPCO 2 gradient ([Formula: see text]) along with the other variables derived from arterial and/or mixed venous blood gases in sodium bicarbonate-treated dogs. Six dogs with low cardiac output following cardiopulmonary resuscitation were used. CO, blood gases, and hemoglobin measurements were repeated every 20-30 min after administration of sodium bicarbonate or normal saline. All measurements were performed after the confirmation of a steady state of CO2 elimination by end-tidal CO2 monitoring. Arteriovenous oxygen content difference ([Formula: see text]), mixed venous oxygen saturation ([Formula: see text]), and[Formula: see text] were highly correlated with CO. The correlation coefficients between[Formula: see text],[Formula: see text], and[Formula: see text] werer=-0.81 (P<0.001),r=0.70 (P<0.001), andr=-0.77 (P<0.001), respectively. The results suggest that, if[Formula: see text] is measured during the steady state, except for the period during the transient increase in CO2 elimination just after the administration of sodium bicarbonate,[Formula: see text] can be used as an index of systemic perfusion even after the administration of sodium bicarbonate.

Hypomagnesemia during pediatric orthotopic liver transplantation.

We evaluated the incidence and severity of serum magnesium (Mg) abnormality along with other electrolyte and acid-base disturbances before and during the course of orthotopic liver transplantation (OLT) in pediatric patients. Serum Mg, Na, K, ionized Ca, pH, and blood gas measurements were performed before and hourly during the course of OLT. Hypomagnesemia was frequently observed in children undergoing OLT. Of a total of 30 recipients, 27 (90%) had hypomagnesemia before surgery; the mean serum Mg value at this time was 0.77±0.15 mmol/L. In most of the recipients, the serum Mg value showed a gradual decrease during the course of OLT until magnesium sulfate supplements were administered. On the other hand, the serum Na, K, and ionized Ca levels and acid-base balance were normal before the beginning of surgery. However, hypernatremia, hypokalemia, a decrease in ionized Ca, and metabolic acidosis were commonly observed during the course of OLT. We conclude that electrolyte abnormalities, including hypomagnesemia and metabolic acidosis, commonly develop in children during the course of OLT. The frequent assessment of electrolytes, pH and blood gases is essential for the correction of these abnormalities during the course of OLT.

[Anesthesia for cesarean section in a patient with transient diabetes insipidus].

A 32-year-old pregnant female was admitted to our hospital at 32 week gestation and was scheduled for emergent cesarean section because of fetal distress. She had been suffering hydrodipsia and dry mouth, and had lost 4 kg in 2 weeks. Hypernatremia, hyperchloremia, and lower urinary specific gravity were preoperatively noted. Her electrolyte imbalance was partially corrected by the infusion of 1400 ml of 5% glucose solution and 500 ml of acetated Ringer's solution, but unexpected hyperglycemia; 440 mg.dl-1, appeared before surgery. Cesarean section was successfully performed with spinal anesthesia. A 1566 g male infant was delivered with 1 and 5 min Apgar scores of 2 and 1. Hyperglycemia and secondary hypoglycemia occurred in the infant in the neonatal ICU. The mother's fluid loss, including blood and amniotic fluid, was estimated at 784 ml. Five hundred milliliters of acetated Ringer's solution and 1000 ml of half saline solution with 2.5% glucose were infused before delivery, followed by the glucose solution containing a low concentration of sodium after delivery. After surgery, high serum osmotic pressure and paradoxically low urinary osmotic pressure were found. The plasma antidiuretic hormone level was normal against the high serum osmotic pressure. The electrolyte imbalance and urinary osmotic pressure were improved by using I-deamino-8-d-arginine vasopressin, and DI was finally diagnosed. Hormonal therapy was discontinued on day 20, and the patient was discharged on day 21. Some pregnancies are complicated by transient DI. Anesthesiologists have to consider DI when a pregnant female has symptoms of dehydration and a significant electrolyte imbalance.