The Excitatory Action of Acetylcholine on Intradental Sensory Units

In order to test the hypothesis that ACh mediates the transmission of pain stimuli from dentin to sensory intradental nerve endings the following experiments were performed. Intradental nerve impulses were recorded by means of low impedance electrodes inserted in dentinal cavities in the tooth of the cat. An air blast proved to be an efficient physical stimulus to excite the intradental nerves. Local application of acetylcholine caused a similar response. This response to acetylcholine was followed by a transient blockage to repeated application. The response to acetylcholine could be blocked by d-tubocurarine, atropine, succinylcholine and hexamethonium administered locally. In contrast, the response to physical stimuli (air blasts) could not be blocked by these drugs. Moreover, during the period of depression following acetylcholine the preparation responded to physical stimuli. These findings suggest that acetylcholine is not a mediator in the intradental pain transmission provoked by physical stimuli.     

Accuracy and choice of procedures in 24-hour oesophageal pH monitoring with monocrystalline antimony electrodes

In 24 h pH monitoring, the evaluation is dependent on the absolute accuracy of the pH measurements. Several sources of error exist, such as the chemical composition of calibration buffers and reference electrode gel and the effect of temperature on both the pH and the reference electrodes. We investigated the magnitude of these errors for the monocrystalline antimony electrode. Similar analysis applies to other types of pH electrodes. The errors we found are important when choosing a calibration procedure. We recommend a calibration procedure in which the pH and reference electrodes are both put in a beaker with the calibration buffers prior to and after the 24 h measurements. The calibration buffers and the electrode gel should have a specially selected ion composition where, for example, the Cl-ion concentration is critical. Corrections for differences in temperature between the calibration and the in situ measurements must be added. The pH measurements can be checked by performing in situ calibration.     

Effects of autonomic reflexes on tooth pulp blood flow in man.

In 15 subjects, laser-Doppler flowmetry (LDF) was used to investigate whether the nervous control of pulpal blood flow (PBF) is affected by three tests known to excite the sympathetic nervous system. For comparison, skin blood flow was similarly recorded. Dynamic exercise (bicycle ergometer, 5 min, 90-100 W) in eight subjects was accompanied by a rise in PBF. PBF was increased by the cold pressor test (2 min) in eight subjects, while in five the flow decreased or remained unaffected. The isometric hand grip (2 min, 30% MVC) and the subsequent muscle ischaemia (2 min) led to a rise in PBF in two subjects and a fall in four. Following unilateral anesthesia of the mandibular nerve, PBF in five subjects became unresponsive to dynamic exercise or the cold pressor test, indicating pressure autoregulation. All three tests triggered increases in mean arterial pressure (MAP) and heart rate (HR). Skin blood flow usually increased in response to the tests, but could also decrease, and often changed in a direction opposite to that of PBF. It is concluded that the circulation of blood in the human tooth is affected by evoked changes in autonomic nerve activity, involving activation of both vasodilator and vasoconstrictor nerves to vessels serving the tooth.     

Symptoms profile and quality of life in rural and urban patients with chronic psychoses

The symptoms profile (modified Positive and Negative Syndrome Scale, PANSS) and the quality of life (Lancashire Quality of Life Profile, LQLP, and the Quality of Life Scale 100, QLS-100) were compared between two groups of patients with chronic psychoses: a rural group of 19 patients living in villages with < or =300-10,000 inhabitants and far away from a large city, and an urban group of 19 patients living in a major city with 250,000 inhabitants. The patients were matched pair-wise for sex, age, global assessment of functioning (GAF) and psychiatric symptoms (modified PANSS, total score). Seventeen of the pairs were diagnosed with schizophrenia, and two pairs with delusional disorder. The symptoms profile indicated more negative symptoms and less positive symptoms for the rural group, compared with the urban group, with a significantly lower degree of spontaneity in the rural group. No group differences were found in the QLS-100, or in the specific quality of life variables according to LQLP. However, the rural group had significantly higher self-rating of the general quality of life variables of the LQLP, i.e. satisfaction with well-being, general health and mental health. The results are discussed in view of a possible relation between negative symptoms and impairments in social cognition and insight.     

The Effect of Extracellular Calcium on Thermal Excitability of the Sensory Units in the Tooth of the Cat

Intradental sensory nerve impulse activity was measured from dentinal cavities in canine teeth of anesthetized cats. No spontaneous activity was usually recorded in cavities filled with isotonic saline. Heat stimulation of 15–20^oC failed to give any impulse activity, while other stimuli, such as air blasts produced bursts of impulses. Lowering extracellular calcium ion concentration. by local application of sodium citrate, sodium oxalate or EDTA, induced impulse activity. Under these conditions, heat produced a rapid increase in discharge activity. which lasted as long as the stimulus was applied. Increased extracellular calcium concentration abolished this response to heat. The present findings show that a change in the extracellular calcium ion concentration modulates the excitability of intradental sensory units, and may thus also modulate the resulting experience of pain.     

On the use of monocrystalline antimony pH electrodes in gastro-oesophageal functional disorders

Monocrystalline antimony electrodes have been shown to be suitable for thein vivo determination of pH in blood, tissue and in the upper gastro-intestinal canal. Thanks to their small dimensions it has been possible to mount them into conventional manometry catheters for oesophageal investigation. The monocrystalline antimony pH electrode has several advantages over the conventional pH glass electrode; better accuracy, shorter rise time, smaller dimensions. The monocrystalline antimony electrode has been used for long-term registration of gastro-oesophageal reflux, for the oesophageal acid clearing test and for identification of the pH gradient zone between the gastric and oesophageal mucosa. Its use in combination with pressure sensors has added a new dimension to the diagnosis of functional disorders in the gastro-oesophageal region.