Perceived general health in relation to oral health status in a rural Kenyan elderly population.

BACKGROUND: This study aimed to determine the present oral health status of the rural Kenyan elderly population and to investigate whether oral health status is associated with the perceived general health. METHODS: A total of 131 individuals aged 65 years and over in Mbita Constituency, Homa Bay County in Kenya were randomly selected and visited at home. The home visit study, which was conducted from 2014 to 2016, included oral examination by a dentist and administration of a self-reporting questionnaire. The number of teeth present and functional tooth unit (FTU) points were calculated using the dental chart. Perceived general health, subjective masticatory ability, and self-reported periodontal symptoms were collected using a questionnaire sheet. Fisher's exact test and nonparametric test were used to determine the difference in percentage and means. The odds ratio of good general health based on the participants' masticatory satisfaction was calculated by logistic analysis. RESULTS: Satisfactory mastication was dependent on the number of teeth present, FTU points, and self-reported "gum bleeding" and "tooth mobility". Furthermore, satisfactory mastication was associated with perceived general health status independent of sex and age. The adjusted odds ratio of good perceived general health was 2.29 (95% confidence interval 1.05-4.99) for participants who had the subjective masticatory ability. CONCLUSION: Among the Kenyan elderly population, satisfactory mastication was related to the number of teeth present, FTU points, and self-reported periodontal symptoms. Furthermore, satisfactory mastication was associated with perceived general health status independently.

Functional effects of cold stimulation on taste perception in humans.

Thermal modulation of signaling pathways leads to excitation of taste receptor cells, but the underlying mechanisms remain unclear. Furthermore, it has long been known that there are contrast effects in various senses. In this study, we investigated cold-taste contrast and the relationship between taste and somatosensation. We lowered intraoral temperature using cold stimulus as a pretreatment, then returned to normal temperature in 249 healthy subjects, before administering room temperature taste-stimulating solutions to investigate changes in sensitivity to the four basic tastes (Sweet, Salt, Sour, and Bitter). Statistical comparisons of taste recognition thresholds before and after cold stimulus showed increased taste sensitivity for all four basic tastes. After categorizing different levels of pre-cold stimulus taste sensitivity into groups and comparing changes in sensitivity to the four basic tastes before and after stimulus, we found that the lower the sensitivity to the four basic tastes, the greater the increase in sensitivity induced by cold stimulus. These findings suggest that taste and low temperature send afferent signals which cause interaction in the afferent pathways between the peripheral and central nervous systems. Cold stimulus may offer one possible treatment strategy for dysgeusia.

Wing (Ib) cells in frog taste discs detect dietary unsaturated fatty acids.

The effects of unsaturated fatty acids on membrane properties were studied using conventional whole-cell patch-clamp recording of isolated wing (Ib) cells in bullfrog (Lithobates catesbeianus) taste discs. Applying arachidonic acid to the bath induced monophasic inward currents in 60% of wing cells and biphasic inward and outward currents in the other cells. The intracellular dialysis of arachidonic acid did not induce an inward current; however, it enhanced a slowly developing Ba(2+)-sensitive outward current. The effects of various unsaturated fatty acids were explored under the condition of Cs(+) internal solution. Linoleic and α-linolenic acids induced large inward currents. Oleic, eicosapentaenoic and docosahexaenoic acids elicited the same inward currents as those of arachidonic acid. Wing cells, under the basal condition with Cs(+) internal solution, displayed a small inward current of -1.1±0.1pA/pF at -50mV (n=40), in which the peak existed at a membrane potential of -49mV. Removing external Ca(2+) further increased the inward current by -2.9±0.3pA/pF at -50mV (n=4) from the basal current and the peak was located at -55mV. External linoleic acid (50µM) also induced a similar inward current of -5.6±0.6pA/pF at -50mV (n=19) from the basal current and the peak was located at -61mV. External Ca(2+)-free saline and linoleic acid induced similar current/voltage (I/V) relationships elicited by a ramp voltage as well as voltage steps. Linoleic acid-induced currents were not influenced by replacing internal EGTA with BAPTA, whereas inward currents disappeared under the elimination of external Na(+) and addition of flufenamic acid. These results suggest that dietary unsaturated fatty acids may depolarize wing (Ib) cells, which affects the excitability of these cells.

Stress-induced modulation of nociceptive responses in the rat anterior cingulate cortex.

In the limbic system, the anterior cingulate cortex (ACCX) is one of the key areas involved in the close association between pain and emotion. However, neuronal changes in ACCX nociceptive responses after stress conditioning have not yet been quantitatively investigated. We investigated the modulation of nociceptive responses in the ACCX neurons following restraint stress in rats. The present study demonstrated that stress-conditioning enhanced excitatory nociceptive responses in the ACCX following tail stimuli in the mid-term (7 days). Short-term (3 days) and long-term (21 days) of stress conditioning did not affect these responses significantly. Nociceptive responses evoked by other sites of the body (nose, back and four paws) stimulation were not changed by stress-conditioning, indicating that neural information from the tail is important for emotional system modulation. It is suggested that the emotional/affective part of the pain sensation is strongly modified by stress through neuroplasticity in the ACCX.

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.

Hypergravity conditioning on ileal movements in rats.

INTRODUCTION: Stress is a common trigger for various physiological disturbances, including feeding disorders. One of the possible mechanisms for feeding disorders may be linked to changes in intestinal movement caused by stress. Therefore, here we investigated in vitro stress-induced changes in ileal movement. METHODS: Rats (female Wistar, SPF) were divided into Control (1 G) and hypergravity (hyperG) groups. HyperG stress was applied daily for 10 min by a centrifugal apparatus for 1 to 30 d. Under barbiturate anesthesia, a 1-cm long section of the ileum was isolated and fixed in a Magnus-type chamber filled with tyrode solution. Intestinal movement was evoked by applying acetylcholine (Ach, 10(-7)-10(-5) g x ml(-1)). Antagonistic effects of adrenalin (Adr, 10(-4) g x ml(-1)) on the Ach-evoked movements were also observed. RESULTS: Clear ileum movements were observed after Ach application. The movement pattern was phasic (early) and tonic (late). Peak amplitude of the phasic wave was dose-dependent on the Ach concentration. No significant differences in the averaged peak amplitude between control and hyperG groups were observed. The peak amplitude was decreased by Adr application in both the control and hyperG groups; however, the degree of the decrement was higher in hyperG than in control at 1 d after stress loading. DISCUSSION: The present study indicates that gravity stress modified ileal movement. Although basic ileum movements evoked by Ach were not influenced by stress, they were modified by Adr at a quite early stage after stress loading, suggesting an increase in the sensitivity of Adr receptors, but not of Ach receptors in the ileum.

Age Differences in Naloxone Reversibility of Electroacupuncture on the Jaw Opening Reflex in Rats.

Background: Electroacupuncture is one of the most popular physical treatments for clinical pain, but the potential influence of a patient's age on the effectiveness of electroacupuncture treatment has not been clearly established. Objectives: The present study aimed to detect a potential difference in electroacupuncture- induced analgesia between juvenile and adult rats. Methods: In this study, we investigated the effects of electroacupuncture treatment on the nociceptive jaw-opening reflex evoked by tooth-pulp stimulation in juvenile and adult rats. Results: Our results showed there were age differences in electroacupuncture-induced analgesic effects in rats, especially with naloxone antagonization. The ratio of naloxonereversibility against electroacupuncture analgesia was greater in adult rats than in juvenile rats. Conclusion: These results suggest that electroacupuncture analgesia is produced mainly by the non-opioid system in juvenile rats and by the opioid system in adult rats.

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.

Apathy and depression in Parkinson disease.

The purpose of this study was to investigate the prevalence and clinical correlates of apathy and depression in Parkinson disease (PD), and to clarify whether apathy can be dissociated from depression. One hundred fifty patients with PD completed the Beck Depression Inventory Second Edition (BDI-II), Starkstein's Apathy Scale (AS), and a quality of life (QOL) battery. Hoehn and Yahr (HY) staging, the Unified Parkinson's Disease Rating Scale (UPDRS), and the Mini-Mental State Examination (MMSE) were performed on the same day. Apathy (AS score > or = 16) was diagnosed in 60% of patients and depression (BDI-II score > or = 14) in 56%. Apathy coexisted with depression in 43% of patients, compared with depression without apathy in 13% and apathy without depression in 17%. Apathy scale score was significantly correlated with UPDRS scores, HY stage, and age, whereas BDI-II score was correlated only with UPDRS scores. Both AS and BDI-II scores were negatively correlated with QOL. However, multiple regression analysis revealed that depression was strongly and negatively associated with emotional well-being and communication, whereas apathy was mainly associated with cognition and stigma. These findings suggest that apathy and depression may be separable in PD, although both are common in patients with PD and are associated with QOL.

Ice cube stimulation helps to improve dysgeusia.

Dysgeusia causes a decrease in appetite, and it is one of the major factors in undernutrition. Dysgeusia is elicited by numerous causes, and in many cases it is still difficult to treat the various symptoms complained of by patients. We herein report a case in which dysgeusia was improved by transient cooling of the mouth.

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.

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.

Effects of midazolam on acquisition and extinction of conditioned taste aversion memory in rats.

Some intravenous anesthetic agents such as midazolam are known to induce anterograde and retrograde amnesia. We analyzed the effect of midazolam by the conditioned taste aversion (CTA) acquisition and retention. After the rats were offered 0.1% sodium saccharin (Sac) as conditioned stimulus (CS), an intraperitoneal (i.p.) injection of several concentrations (5-30mg/kg) of midazolam was followed by an i.p. injection of 0.15M LiCl (2% of body weight) as unconditioned stimulus (US). The rats, which acquired CTA by every CS-US paradigm, strongly avoided Sac on the 1st test day after conditioning and maintained the avoidance for 3 days. We have already reported that Sac intake abruptly increased on the 2nd test day and the almost complete extinction occurred on the 3rd test day after conditioning by injection of subhypnotic dose of propofol before LiCl-injection. In contrast, we found that subhypnotic dose of midazolam suppressed not only CTA acquisition, but also CTA retention. On the other hand, an alpha2-adrenergic blocker, yohimbin (1mg/kg) suppressed only the CTA retention. These results suggest that the subhypnotic doses of midazolam firstly affect the acquisition mechanism of the CTA memory (CTAM), resulting the suppression of the retention of CTAM.

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.

Disinhibitory involvement of the anterior cingulate cortex in the descending antinociceptive effect induced by electroacupuncture stimulation in rats.

The present study was conducted to clarify the role of the anterior cingulate cortex (ACCX) in acupuncture analgesia. Experiments were performed on 35 female Wistar albino rats weighing about 300 g. Single unit recordings were made from ACCX neurons with a tungsten microelectrode. Descending ACCX neurons were identified by antidromic activation from electrical shocks applied to the ventral part of the ipsilateral PAG through a concentric needle electrode. Cathodal electroacupuncture stimulation of Ho-Ku (0.1 ms in duration, 45 Hz) for 15 min was done by inserting stainless steel needles bilaterally. An anodal silver-plate electrode (30 mm x 30 mm) was placed on the center of the abdomen. Naloxone (1.0 mg/kg, i.v.) was used to test whether changes of ACCX activities were induced by the endogenous opioid system. Data were collected from a total of 73 ACCX neurons. Forty-seven neurons had descending projection to the PAG, and the other 26 had no projections to the PAG. A majority of descending ACCX neurons were inhibited by electroacupuncture stimulation. By contrast, non-projection ACCX neurons were mainly unaffected by electroacupuncture. Naloxone did not reverse acupuncture effects on the changes of ACCX neuronal activities. Acupuncture stimulation had predominantly inhibitory effects on the activities of descending ACCX neurons. Since the functional connection between ACCX and PAG is inhibitory, electroacupuncture caused disinhibition of PAG neurons, whose activity is closely related to descending antinociception to the spinal cord. This disinhibitory effect elicited by acupuncture stimulation is thought to play a significant role in acupuncture analgesia.

Emotional stress- and pain-related behaviors evoked by experimental tooth movement.

OBJECTIVE: To investigate by behavioral methods the relationship between emotional stress and pain during experimental tooth movement in rats. MATERIALS AND METHODS: Sixteen male Sprague-Dawley rats (210 to 250 g) were divided into two groups. The experimental group was treated with an active Ti-Ni appliance, and the control group received a passive appliance. A force of 20 gf was delivered by the active appliance between the maxillary first and second molars for 3 days. During this period the rat's behavior was evaluated eight times by means of open-field test and resistance-to-capture test. The specific parameters of animal activity were facial grooming, rearing, and locomotor activity, movement into the center of the open field, and response to capture. RESULTS: Parameters related to stress and pain were higher in the group carrying active appliance, compared to the group with a passive appliance. Statistically significant differences in stress-related behavior between control and experimental groups were found 8 hours after placing the appliance and were most evident on the second day. Pain-related behavior was significantly greater in the experimental group than in the control group at 24 hours. CONCLUSIONS: The increase in emotional stress evoked by orthodontic tooth movement may precede the appearance of periodontal pain.

Splenius muscle activities induced by temporomandibular joint stimulation in rats.

Recent studies show that temporomandibular joint disorders cause hyperalgesia and deficits in the postural control of cervical region. However, the effects of specific modalities of receptors in the temporomandibular joint area on these phenomena are still unclear. In this study, we investigated the neck muscle activities while natural mechanical stimulation was applied to the temporomandibular joint. Single motor unit activities were recorded bilaterally from the splenius muscles in 22 Wistar rats. Mechanical stimulation applied to the left temporomandibular joint elicited tonic discharges in the left or right splenius muscle. The mean threshold values for mechanical stimulation were 48.1 (+/-16.2 S.E.M.) and 54.1 mN (+/-16.3 S.E.M.) for left and right sides, respectively. It is suggested that the temporomandibular joint mechanoreceptors not only affect the motor unit activities of neck muscles, but also are concerned in the regulation of postural control of the head.

Periodontal masseteric reflex is changed by periodontal sensory modification during occlusal hypofunction in rats.

The purpose of this study was to investigate changes in the periodontal masseteric reflex (PMR) after experimentally induced occlusal hypofunction. Wistar rats were divided into control groups (CGs) and hypofunction groups (HGs). Rats in the HGs had their lower incisors cut down every other day for 6 weeks. Electrical stimulation was given to the periodontal ligaments of an upper incisor or the left trigeminal mesencephalic nucleus (MeV) in the CGs and HGs. Recordings of masseter motor unit responses were performed at 0, 1, 2, 4 and 6 weeks after hypofunction. Compared with the CGs, significant longer latencies in the PMR were found in the 4w- and 6w- HGs. After MeV stimulation, no significant difference in latency was found between HGs and CGs. After periodontal stimulation, the threshold value of masseteric motor-unit responses was higher in HGs than in CGs in 4and 6 weeks respectively. These results suggest that the PMR can be changed by periodontal sensory modification during occlusal hypofunction.

Functional changes of the temporomandibular joint mechanoreceptors induced by a lateral mandibular shift in rats.

OBJECTIVE: To investigate changes in functional characteristics of the temporomandibular joint (TMJ) mechanoreceptors under mandibular lateral shift. MATERIALS AND METHODS: Forty 7-week-old male Wistar rats were divided into control and experimental groups. Rats in the experimental group received a modified guiding appliance (MGA) that was designed to shift the mandible to the left side in the occlusal position. Single-unit activities of the TMJ mechanoreceptors were evoked by indirect stimulation of passive jaw movement. Electrophysiologic recordings of TMJ units were obtained 1, 3, 5, 7, and 9 weeks after MGA setting from the gasserian ganglion. RESULTS: At 1 week after mandibular shift, the firing thresholds were the lowest and the maximum instantaneous frequencies were the highest in TMJ units. At 5 weeks, the firing thresholds in the nonshifted side were significantly lower than those in the shifted side. The maximum instantaneous frequencies in the nonshifted side were significantly higher than those in the shifted side at 1, 5, and 7 weeks. CONCLUSION: These results suggest that the functional lateral shift of the mandible could alter the response properties of TMJ mechanoreceptors, particularly on the nonshifted side.

SURVEY OF DENTAL STUDENTS' ATTITUDE REGARDING ORIENTAL MEDICINE/COMPLEMENTARY AND ALTERNATIVE MEDICINE: COMPARISON BETWEEN TWO JAPANESE DENTAL SCHOOLS.

BACKGROUND: The present study aimed to examine the impact of "curricula for undergraduate education in oriental medicine (OM)/complementary and alternative medicine (CAM)" on student awareness of OM. A questionnaire survey was conducted involving the Nagasaki University School of Dentistry (NUSD), a university that implements education in OM as part of its undergraduate curriculum, and Tokyo Dental College (TDC), which does not teach OM. MATERIALS AND METHODS: The third- and fifth-year students of both NUSD and TDC underwent the anonymous questionnaire survey, which included questions regarding their knowledge of OM and CAM, interests in these subjects, and their opinions on the necessity of teaching OM in the undergraduate dental education, and the results were collected for analysis. RESULTS: Whereas 33% of 5th year NUSD students had knowledge of OM/CAM was 33%, only 10% of 5th year TDC students reported knowledge on the subject. 69% of 5th year NUSD students interested in OM/CAM, while 5th year TDC students who interest them were only 45%. Although 77% of 5th year NUSD students were in favor of OM education implemented in the Faculty of Dentistry, the percentages of TDC students of that were smaller (46% in 3rd year and 48% in 5th year). Whereas 26% of 5th year TDC students did not recognize the necessity of oriental medicine education, only one 5th year NUSD student (2%) did not so. CONCLUSION: Introduction of education in OM in the undergraduate dental education program helps students to increase their interests in dental clinical applications.