Somatosensory tinnitus and temporomandibular disorders: A common association.

BACKGROUND: Although the association between tinnitus and temporo-mandibular disorders (TMD) has been frequently reported, their rate of association in the literature shows a great variability. OBJECTIVE: We aimed to investigate the prevalence of TMD in patients with somatosensory tinnitus and, vice versa, the occurrence of somatosensory tinnitus in patients with TMD. METHODS: The study included patients with somatosensory tinnitus (audiological group) and patients with TMD (stomatological group), evaluated at the audiologic and stomatologic clinics of the Policlinic Hospital of Milan, Italy. Common causes of tinnitus, such as hearing and neurological disorders, were excluded. A cervicogenic somatic tinnitus was also ruled out. Different TMD symptoms, including joint noise and joint pain, were considered. The collected data were analysed using descriptive statistical methods, and the Pearson's Chi-squared test was performed to study the prevalence of the different symptoms by clinical groups. RESULTS: Audiological group included 47 patients with somatosensory tinnitus. Overall, TMD was diagnosed in 46 patients (97.8%), including TMJ noise in 37 (78.7%), clenching in 41 (87.2%) and pain in 7 (14.8%) patients. Stomatological group included 50 patients with TMD, including joint noise in 32 (64.0%), clenching in 28 (56.0%) and TMJ pain in 42 (84.0%) patients. A somatosensory tinnitus was diagnosed in 12 (24.0%) patients. CONCLUSION: Our study showed a high prevalence of TMD in patients with tinnitus, as well as a not uncommon occurrence of tinnitus in patients presenting with TMD. The distribution of TMD symptoms, such as joint noise, and joint pain was different between the two groups.

Evaluation of the performance of the first automatic milking system for buffaloes.

The objective of this study was to evaluate the response of buffaloes to automatic milking, examining the relationships between milking interval, milk production, and milking time for this species. A total of 7,550 milking records from an average of 40 buffaloes milked by an automatic milking system (AMS) were analyzed during a 3-mo experimental period at a commercial farm with Italian Mediterranean buffaloes in southern Italy. Date and time of animal identification, milk yield, milking duration, milking interval, and average milk flow rate were determined for each milking. The results were also used to predict the maximum number of milkings per day and the optimal number of buffaloes per AMS for different levels of milk production. The average interval period between 2 consecutive milkings was 10.3 h [standard deviation (SD) 3.3]. Overall, 3.4 and 25.7% of the milkings had an interval of ≤ 6 h or >12 h, respectively. Milking duration averaged 8.3 min per buffalo per milking (SD 2.7). The average milk flow rate was 1.3 kg/min (SD 0.5) at a milk yield of 2.8 kg per milking (SD 1.4). Assuming that the milking station is occupied 80% of the time, the number of milkings ranged from 136 to 152 per day and the optimal number of buffaloes per AMS ranged from 59 to 66 when the production level increased from 2 to 5 kg of milk per milking. Automatic milking systems are suitable for buffalo, opening new options for the management of dairy buffalo farms.

Salivary pH after a glucose rinse: effect of a new mucoadhesive spray (Cariex) based on sodium bicarbonate and xylitol.

OBJECTIVE: This study evaluated whether sodium bicarbonate applied on the oral mucosa through a new mucoadhesive spray (Cariex) could control a drop in salivary pH after a glucose rinse, and therefore enhance the buffering potential of saliva. METHODS: A sample of 50 healthy adults was selected. At day 1, the measurement of salivary pH was performed in the lower fornix in correspondence with the lower molars. Each subject rinsed with 10 ml of a 10% glucose solution and then pH was monitored continually for 40 minutes. At day 2, the same experimental procedure was repeated and three shots of the spray were administered on the oral mucosa. The tested spray is composed of sodium bicarbonate, xylitol, and excipients. RESULTS: Without the mucoadhesive spray, salivary pH became significantly lower following the glucose rinse (p < 0.01). Following the spray, the time in which the pH remained lower than 6.0 was reduced statistically significantly (p < 0.01). A continual rise of salivary pH was observed for the 40 minutes in which the pH recording was performed. Conclusions: The use of a sodium bicarbonate spray on the mucosa was shown to control the lowering of salivary pH following carbohydrate consumption, and might therefore add to the prevention of caries and dental erosion.

pH of tooth surface in healthy adolescents at rest and after a glucose rinse: effect of 72 hours of plaque accumulation.

AIM: This study was performed to evaluate the effect of a glucose rinse and of plaque accumulation on pH of tooth surface in healthy adolescents with a device used in gastroenterology and never tested in the oral cavity. MATERIALS AND METHODS: Values of pH were monitored in 12 adolescents using a portable device (pH-day 2® Menfis, bioMedica S.r.l., Bologna, Italy) with a disposable antimonium electrode kept in contact with the interproximal surface of the upper molars for 40 minutes respectively before and after a one-minute rinse with 10 ml of a 10% glucose solution. The same procedure was repeated in the same subjects after 72 hours of plaque accumulation. RESULTS: The device tested resulted difficult to use on the tooth surface because of the size of the active part of the probe. The glucose rinse caused a statistically significant decrease of the mean pH, restrained in basal conditions (d = -0.16, p <0.05), clinically relevant after plaque accumulation (d = -1.24, p <0.05). Time in minutes of pH < 6 grew considerably only in case of combination of plaque accumulation and glucose rinse (d = 20.90, p <0.05). A Stephan's curve of drop and recover of the pH values was not recorded. CONCLUSIONS: The continuous recording of pH of natural plaque present on the tooth could represent an alternative to other techniques found in literature. More studies are necessary to verify the suitability of this new device for the monitoring of pH in the oral cavity.

Effects of the working vacuum level on mechanical milking of buffalo.

Mechanized milking has become widely used for buffaloes in Italy in recent years, thus improving the management and the productivity of farms. The apparent similarities between buffalo and cattle have often resulted in applying the same milking systems and techniques currently used for dairy cows. Considering the effect of mechanical milking on animal health, productivity, and welfare in intensive livestock farming, this study compares the effects of milking at low vacuum (36 kPa) and medium vacuum (42 kPa) on milk emission characteristics and milking system performance. Individual milk flow curves were registered to analyze milk yield, average flow rate, and milking time, and milking operations were recorded to evaluate the system performances. When using 36 kPa vacuum, a significant increase in milking time and in the lag time before milk ejection occurred, as well as a decrease in average flow rate and residual milk. However, the vacuum level did not influence both milk yield and milk ejection time. As a consequence of decreasing the vacuum level to 36 kPa, the milking system throughput was decreased at most by 5 buffalo/h.

Sudden death in epilepsy: an experimental animal model.

INTRODUCTION: The physiopathogenetic mechanisms possibly involved in sudden unexplained epileptic death (SUDEP), were investigated in the hemispherectomized rat. METHODS: For this purpose, paroxysmal activity, vagal nerve firing, systemic blood pressure (BP), pulmonary artery pressure, and ECG were simultaneously recorded in an experimental animal model of epilepsy. Recordings were performed in basal conditions and during paroxysmal activity induced by topical application of penicillin-G at hypothalamic and mesencephalic level. During the experiment were also performed hemogas analysis and at end, samples of lung tissue were processed for histology. RESULTS: Activation of hypothalamic (HEF) and mesencephalic (MEF) epileptic foci induced a significant increase of spontaneous vagal nerve firing that was strictly correlated to ECG impairments and hypotension. When paroxysmal activity extinguished, vagal nerve activity and cardiovascular parameters returned to basal conditions. However, in 25% of the animals, co-activation of HEF and MEF always triggered a vagal hypertone which was temporally correlated to cardiac arrhythmias, but also to hyperkalemia, acidosis, pulmonary hypertension and to animal death. Histological control in lungs of deceased animals showed an alveolar and perivessel oedema with an oedematous infiltration in the alveolar and bronchial spaces and mucous secretion. During ictal activity, comparison between survived and deceased animals showed significant differences in the incidence of ECG impairment of pulmonary artery pressures, pO2, and pCO2 pressures, and [K+], [HCO3-], and [pH], concentrations. DISCUSSION: A possible explanation of the above observations is discussed in relationship to SUDEP physiopathogenesis.

Information processing within the motor cortex. I. Responses of morphologically identified motor cortical cells to stimulation of the somatosensory cortex.

Inputs from the somatosensory cortex to the motor cortex have been proposed to function in learning of motor skills. In an attempt to analyze how these somatosensory inputs were processed in the motor cortex, neurons in the superficial layer of the cat motor cortex were classified into three groups on the basis of synaptic responses elicited by intracortical microstimulation (ICMS) of area 2. ICMS was delivered through seven electrodes implanted in area 2. When ICMS through one of the seven sites produced a response that was greater than 50% of the response produced by stimulating the seven sites at a time, the site was called a "dominant" site. Type I cells were those that had a dominant stimulation site and showed a constant response latency when examined by a double shock test. Type II cells were those that had a dominant site but displayed a variable latency. Type III cells had no dominant site and showed a variable latency. Latency of type I responses was 1.2-2.6 milliseconds, which was much shorter than that of type II and type III responses. Seventy-nine neurons in layers II/III of the motor cortex, which responded to ICMS in area 2, were stained by intracellular injection of biocytin. From the presence of an apical dendrite and rich spines on the dendrites, 23 type I, 21 type II, and 15 type III cells were classified as pyramidal cells. Type II pyramidal cells were located more superficially than type I and type III pyramidal cells. On the basis of the absence or sparseness of dendritic spines, three type I and four type II cells in layers II/III were classified as nonpyramidal cells. These cells consisted of five small multipolar cells in layer II and a large multipolar cell and a small bitufted cell in layer III. The remaining 11 cells were not classified because of insufficient staining. Since type I and type II cells are considered to represent monosynaptic and polysynaptic responses to stimulation of area 2, respectively, information flow from type I cells to more superficially located type II cells is presumed in layers II/III of the motor cortex. Type III responses suggest the presence of a convergent flow of impulses inside of and/or between areas 2 and 4.

Information processing within the motor cortex. II. Intracortical connections between neurons receiving somatosensory cortical input and motor output neurons of the cortex.

Connections between motor cortical neurons receiving somatosensory inputs from area 2 and large pyramidal cells in layer V were examined in the cat via intracellular injection of biocytin and immunohistochemistry of nonphosphorylated neurofilament proteins (npNFP). Biocytin was injected into pyramidal cells in layers II/III of the motor cortex that responded monosynaptically and polysynaptically to microstimulation of the somatosensory cortex and subsequently stained black by the avidin-biotinylated peroxidase complex method with diaminobenzidine (DAB) and nickel. By using a monoclonal antibody SMI-32 and a modified peroxidase-antiperoxidase method with Tris-aminophenyl-methane (TAPM) and p-cresol as a chromogen, pyramidal cells in layers III and V of the motor cortex were stained red for npNFP. In particular, all the large pyramidal cells in layer V, Betz cells, displayed intense npNFP immunoreactivity not only in the perikarya but also in the dendrites. Double staining with DAB/nickel and TAPM/p-cresol showed that biocytin-filled axon varicosities of the pyramidal cells, which were thought to receive monosynaptic inputs from area 2, made contacts with npNFP-positive dendrites in layers I-III around the biocytin-injected cell and in layers V-VI beneath the cell. The present results suggest that the corticocortical input from area 2 to pyramidal cells in layers II/III of the motor cortex is transferred to layer V pyramidal cells, including Betz cells, as well as to neighboring layer II/III pyramidal cells. Since tetanic stimulation of the somatosensory cortex reportedly produces long-term potentiation in layer II/III cells of the motor cortex, it seems reasonable to assume that a given area of the somatosensory cortex can produce a long-lasting change in the activity of a given group of output cells in the motor cortex.

T cell activation through different membrane structures (T3/Ti, T11, T44) and frequency analysis of proliferating and interleukin-2 producer T lymphocyte precursors in aged individuals.

It is well known that the proliferative responsiveness of T cells of aged subjects is depressed in both autologous mixed lymphocyte reaction (AMLR) and in PHA-induced cultures. In the present study we analyzed T cell activation through different stimulatory pathways (such as T3/Ti antigen receptor, T11 complex and T44 molecule). Moreover, we studied Interleukin-2 (IL-2) release performing a limiting dilution analysis of the proliferative capability of peripheral blood T cells, employing a high efficiency cloning technique. Our results demonstrate normal proliferation of T3-induced T cells in aged subjects, whereas T11- and T44-induced T cell proliferations are depressed in aged subjects. In addition, studies at clonal level reveal a normal percentage of IL-2 producer T cell in aged individuals. In conclusion, our data suggest that the T cell in aged subjects are normal in number, but they have a decreased capacity of lymphokine production.

Defect of autologous mixed lymphocyte reaction and interleukin-2 in aged individuals.

The proliferative responsiveness of T cells of aged individuals is known to be depressed in both autologous mixed lymphocyte reaction (AMLR) and in PHA-stimulated cultures. In the present study we confirm previous results and also report decreased IL-2 and normal IFN-gamma production (PHA-induced) in aged subjects as compared to young normals. In addition, similar percentages of T lymphocytes expressing surface IL-2 receptors both in the peripheral blood and after different stimulations, i.e. AMLR and PHA, were detected in young and aged individuals. The addition of exogenous IL-2 induces a sharp increase of spontaneous and AMLR proliferation in young individuals, whereas the increase is only slight in aged subjects. The experiments reported herein suggest that in general the T cell proliferation in AMLR is not completely dependent on the presence of IL-2 in the cultures and that aged subjects are probably defective in the production of other factor(s) presumably involved in AMLR proliferation, since the addition of exogenous IL-2 does not produce T-cell proliferation comparable to normal young subjects. The possible meanings of these experimental evidences in AMLR and in the defective immune responses of aged subjects are discussed.

Functional study of T lymphocyte responsiveness in patients with dementia of the Alzheimer type.

The autologous mixed lymphocyte reaction (AMLR) was used to study T lymphocytes in a group of patients with dementia of the Alzheimer type (DAT) in order to confirm the observation that their T cell proliferation in AMLR was greater than in age-matched controls, and to investigate other pathways of T cell activation, searching for correlations between immunologic and clinical findings in DAT. The mean proliferative response in AMLR was increased in patients with DAT. No differences between patients and age-matched controls were detected when other pathways of T cell activation were investigated. The degree of response in the AMLR varied among patients with DAT. This fits with the suggestion that the disorder may be a heterogeneous syndrome.

Long-term potentiation within the cat motor cortex.

Synaptic plasticity in the motor cortex of anesthetized cats was examined using intracellular recording and labeling techniques. Intracortical microstimulation (ICMS) was delivered in the superficial layers and recordings were made from cells in layer V. When the neuron responded to ICMS with an excitatory postsynaptic potential (EPSP), tetanic ICMS (100-200 Hz, 10-20 s) was delivered to the same site. Five of 19 cells which were examined and labeled with biocytin showed long-term potentiation (LTP) of the EPSP, and 12 cells showed post-tetanic potentiation (PTP) following the tetanic stimulation. All the examined cells were pyramidal neurons. These results demonstrate that plasticity exists within the intracortical connection of the motor cortex that may be involved in motor learning.

Frequency-dependent LTP/LTD in guinea pig Deiters' nucleus.

Synaptic plasticity was studied in the lateral vestibular nuclei (LVN) of the guinea pig in vivo. High frequency stimulation (HFS) of increasing or decreasing frequencies was applied to the ipsilateral vestibular nerve. Vestibular field potentials (VFPs) and extracellular single unit activity evoked in the LVN by electrical stimulation of the ipsilateral vestibular nerve, were analyzed before and after the application of different protocols of HFS. Results show that the monosynaptic component of the VFPs undergo long-term potentiation (LTP) with stimulation of 100 Hz applied for 20 s lower frequencies, applied for shorter periods, induce only a transient post-tetanic potentiation. This potentiation, although long lasting, is not permanent since it is susceptible of a reversal or cancellation by opposite patterns of HFS that determine a depression or depotentiation of the previously acquired potentiation. The results demonstrate that the plasticity phenomena that take place at the level of the LVN neurons are not steady but undergo continuous adjustment of their sign and gain depending on the variable flow of vestibular information that reach the nuclei from the labyrinthine receptors.

Does long-term potentiation occur in guinea-pig Deiters' nucleus?

Long-term potentiation (LTP) was studied in the lateral vestibular nucleus (LVN-Deiters' nucleus) in guinea-pigs in vivo. Field potentials and extracellular single unit discharges were recorded in the LVN following electrical stimulation of the ipsilateral VIIIth nerve. High-frequency stimulation (HFS) of the VIIIth nerve fibres produced LTP of the monosynaptic component of the vestibular field potential. The LTP of the field potentials was paralleled by an increase of the evoked spike activity. Intranuclear administration of the NMDA antagonist MK-801 prevented LTP of the monosynaptic component of the vestibular field potentials and significantly suppressed the spontaneous firing of lateral vestibular neurones in a dose-dependent fashion. These results demonstrate that synapses between primary afferent fibres and second order LVN neurones undergo long lasting changes following HFS of the ipsilateral vestibular nerve.

Labyrinthine projection to the hypoglossal nucleus.

Evoked potentials and responses of single hypoglossal neurons were recorded in response to electrical stimulation of the labyrinth. In addition, the spontaneous electrical activity of hypoglossal neurons was significantly modified in response to ipsi- and contralateral static tilt of the whole animal and thermic stimulation of the labyrinth. The experiment showed that the labyrinth modulates the electrical activity of hypoglossal neurons with phasic inputs in response to ampullar stimulation and with tonic inputs in response to macular stimulation. The vestibular phasic influence of hypoglossal neurons represents the most adequate functional pattern to obtain a quick, short lasting response of the tongue muscles instantly modifiable with every abrupt head displacement. On the contrary, the vestibular tonic influence of hypoglossal neurons represents the most adequate functional pattern to obtain not only adjustment but also maintenance of the muscular lingual response to static displacement of the head.

Neurotoxic effect of lead at low concentrations.

The effects of lead exposure at low concentrations were evaluated by studying the post-rotatory nystagmus (PRN) in two groups of rats exposed for 3 months to 50 parts per million (ppm) of sodium acetate and 50 ppm of lead acetate, respectively, in the drinking water. Only animals treated with lead acetate showed changes of the PRN parameters which were significantly related to the concentration of lead in the blood and in brain structures. The patterns of PRN responses were characterized and classified into four types: progressively inhibitory (40%), prematurely inhibitory (25%), late inhibitory (25%), and excitatory-inhibitory (10%). No alterations of the PRN parameters were observed in the animals treated with sodium acetate. The results show that exposure to lead, even at low concentrations, impairs both sensory and motor functions. The findings also point out that the vestibular system and brain stem structures which generate and control the PRN represent targets of the action of this heavy metal. Finally, the results indicate that the evaluation of the vestibulo-ocular-reflex can provide a test suited for the screening of the neurotoxic effects of lead even in the absence of clinical signs typical of lead intoxication.

Analysis of central cardioarrhythmogenic triggers in experimental epilepsy.

The cardioarrhythmogenic potential of epileptic foci induced at mesencephalic and rhombencephalic levels was analyzed in hemispherectomized rats. Topical application of penicillin-G onto the mesencephalic quadrigeminal lamina or onto the fourth ventricle induced paroxysmal activity at the mesencephalic or bulbar neurone level. At the mesencephalic levels, the paroxysmal activity was characterized by a significant increase in the spontaneous frequency of the neurones, with the appearance of multiunit activity and rhythmical outbursts. The simultaneous recording of myocardial electrical activity and blood pressure showed that the paroxysmal activity triggered short-latency sinus bradyarrhythmias with wandering of the sinus pacemaker, the appearance of biphasic or negative P waves, some premature ventricular contractions and non-significant reduction of systolic and diastolic pressures. When the paroxysmal activity stopped, the cardiac rhythm and blood pressure returned to basal values. At the bulbar level, the paroxysmal activity appeared with longer latency and usually the rhythmical outbursts were not observed. Following bulbar paroxysmal activity only short-lasting episodes of sinus bradyarrhythmias appeared. Midcollicular transection eliminated paroxysmal activity at the bulbar level, and blood pressure and cardiac rhythm resumed basal values. After transection, an additional application of convulsant drug (penicillin-G or pentylenetetrazole) onto the fourth ventricle did not induce the reappearance of paroxysmal activity and the consequent cardiovascular alterations. The results showed the existence of a cardioarrhythmogenic trigger localized at the mesencephalic level which spreads paroxysmal activity upwards. A hypothesis to explain the appearance of fetal haemodynamic modifications and life-threatening arrhythmias has been proposed.

Penicillin-induced paroxysmal activity in brainstem neurons.

The spontaneous electrical activity of single mesencephalic and bulbar neurons was recorded in hemispherectomized rats, following topical application of the GABA-antagonist penicillin-G on the mesencephalon or on the rhombencephalon, to investigate whether these structures could develop a specific penicillin paroxysmal activity independently of the upper structures. Twenty minutes following penicillin-G, the mesencephalic neurons developed paroxysmal activity characterized by a significant increase in the spontaneous electrical activity, the appearance of multiunit activity and, frequently, phasic activity with rhythmical outbursts. The paroxysmal activity at bulbar level appeared later than that observed in the mesencephalon and was characterized by a significant increase of the spontaneous firing rate of the neurons, single short bursts and sometimes rhythmical outbursts. The bulbar outbursts always discharged at lower frequency than those at the mesencephalic level. Following a midcollicular transection the paroxysmal bulbar activity abruptly disappeared. This phenomenon might be explained by a loss of facilitation from superior structures on the bulbar neurons which in roditors show a poor GABA-receptor distribution. In other words, penicillin alone, due to the scarcity of GABA receptors, might not be sufficient to induce paroxysmal activity in bulbar neurons but the simultaneous presence of both the superior facilitation and the drug might enhance neuronal excitability to a critical level. However, the diffusion of the drug upwards to the mesencephalon, with consequent activation of a system allowing the downward propagation of paroxysmal activity, cannot be excluded. In conclusion, while the mesencephalic neurons demonstrate a proper ability to develop penicillin paroxysmal discharge, the bulbar neurons must be sustained by intact connections with upper structures to be able to do so.

Beta-endorphin and cortisol levels in plasma and CSF following acute experimental spinal traumas.

beta-endorphin and cortisol were measured in cerebrospinal fluid (CSF) and plasma by radioimmunological method (RIA) in two groups of rabbits with spinal cord traumatic injuries at cervical and lumbar levels, respectively with and without concomitant spinal shock and arterial hypotension, and in a group of sham operated animals as controls. The two groups with spinal lesions displayed a significant beta-endorphin increase in CSF, whereas the cortisol level remained unchanged both in the spinal traumatized rabbits and in controls. Both the opioid and the cortisol concentration rose significantly in plasma in all three groups and in particular resulted significantly higher in the cervical traumatized group where spinal trauma was associated with spinal shock and hypotension. However, no significant difference was found when beta-endorphin concentrations in plasma were compared between the sham operated animals and the spinal lumbar traumatized animals without concomitant spinal shock. The results seem to suggest that the beta-endorphin increase in CSF is related to the nervous tissue lesion, while its increase in plasma, like that of cortisol, is due to surgery or other stress factors inherent in the experiment. This independent behaviour of beta-endorphin in plasma and in CSF suggests its different origin in these two compartments.

Genotoxicity assessment of aromatic amines and amides in genetically engineered V79 cells.

A genetically engineered V79 cell line expressing rat CYP1A2 and another cell line expressing rat CYP1A2 as well as endogenous acetyltransferase activity, as well as CYP-deficient parental V79 cell lines, were used to assess the genotoxicity of the aromatic amines and amides 2-aminoanthracene, 2-aminofluorene, 2-acetylaminofluorene, 4-acetylaminofluorene and 2-amino-3-methylimidazo[4,5-f]quinoline, with chromosomal aberrations and sister chromatid exchanges as the end-points. None of the test compounds showed a clear effect on the frequency of chromosomal aberrations in any cell line used. Sister chromatid exchanges, however, were induced by 2-aminoanthracene, 2-aminofluorene and 2-acetylaminofluorene in the CYP1A2-proficient cells, but not in the CYP1A2-deficient cells. The presence of acetyltransferase activity enhanced the effect of 2-aminoanthracene, 2-aminofluorene and 2-acetylaminofluorene. 4-Acetylaminofluorene and 2-amino-3-methylimidazo[4,5-f]quinoline did not induce sister chromatid exchanges in the investigated cell lines. The use of cell lines with defined metabolic capabilities seems to be a valuable tool to study specific metabolic pathways important in the activation of procarcinogens.