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Biomedical subjects

R L Speirs

Publications and source records attributed to R L Speirs.

At least 19 recordsLinked to original sources
PubMed1995

Hyperventilation in the dental chair.

An anxious patient may experience an uncontrollable increase in ventilatory effort, far in excess of the body's metabolic needs, to such a degree that profound changes are induced in the cardiovascular and neurological systems. This abnormal drive to breathe rapidly leads to a reduction in the tension of carbon dioxide in alveolar gas and arterial blood and to mild alkalosis. The outward expression of these disturbances can be alarming for both patient and dentist, but for the physiologist searching for underlying mechanisms it is intriguing. The cursory coverage of this subject in some textbooks and lecture courses is regrettable when one considers that hyperventilation is not uncommon in a dental patient. This article examines the causes, signs, symptoms and management of acute hyperventilation.

Dental Anxiety↗
PubMed1992

Food and oral health: 2. Periodontium and oral mucosa.

Dental schools tend to teach only the rudiments of this subject and this does not provide a good basis for dentists to advise patients and combat the misinformation surrounding the topic. The first article in the two-part series examined nutrition as it applies to dental caries, while part two discusses some of the general principles of nutrition in relation to oral health, periodontal disease and the oral mucosa.

Aged↗
PubMed1992

Food and oral health: 1. Dental caries.

Dental schools tend to teach only the rudiments of this subject and this does not provide a good basis for dentists to advise patients and combat the misinformation surrounding the topic. The first article in the two-part series examines nutrition as it applies to dental caries, while part two will discuss some of the general principles of nutrition in relation to oral health, periodontal disease and the oral mucosa.

Animals↗
PubMed1992

Stress and the immune system.

The centuries-old belief that stressed individuals are more susceptible to disease has gained scientific respectability in recent years. A new interdisciplinary science, psychoneuroimmunology (or as it is now more appropriately named, psychoneuroendocrinimmunology) has been born and, judging from the number of articles appearing annually, is thriving. In essence, stressors activate the neuroendocrine axis, which in turn influences the immune system. This is a bidirectional process, since chemicals are released by activated immunological cells which alter the functioning of the endocrine and autocrine nervous systems and influence our behaviour. This article examines these interactions.

Disease Susceptibility↗
PubMed1991

Haemostasis.

Normal haemostasis depends on a balance between coagulation and fibrinolytic processes. Because of this concept of balance between coagulation and fibrinolysis, drugs which retard or inhibit the breakdown of fibrin encourage haemostasis. Such drugs are used in patients undergoing dental extractions and as prophylactic agents to prevent spontaneous bleeding. Blood clotting factors produced by genetic engineering are now becoming available and these offer exciting prospects for the management of patients with bleeding disorders.

Blood Coagulation Disorders↗
PubMed1990

Phosphoprotein extraction from the dentine/cementum complex of human tooth roots.

Root shards were placed in dialysis tubing and demineralized to completion in either 10% disodium EDTA, pH 7.4, 0.6 M HCl, 0.1 M HCl, 0.5 M acetic or 75 mM-25 mM lactic-acetic acids. The demineralized shards were then re-extracted with 0.05 M tris-HCl, 1.0 M NaCl. DEAE chromatography revealed that the major peak of the 0.6 M CHl and EDTA extracts contained organic phosphorus, whereas much less organic phosphorus was found in the major peak of the 0.1 M HCl extract. Analysis of the re-extracts gave a pattern opposite to that obtained from the initial extractions. Measurements of protein and organic phosphorus released during extraction and re-extraction confirmed these results. Staining of SDS-PAGE gels for phosphoprotein with Stains-All resulted in a blue smear in fractions containing organic phosphorus. Thus the extraction of phosphoproteins from human tooth roots differed depending upon the demineralizing conditions. This ability to remove phosphoprotein differentially will allow further investigation of the role of phosphoprotein in mineralization and remineralization.

Acetates↗
PubMed1989

Toffee clearance and lingual sensory and motor activities in normal children and in children with articulation problems of speech.

The rate at which a standardized mouthful of toffee containing technetium (99mTc) tin colloid was cleared from the mouth during and after chewing was measured by counting the residual radioactivity in the mouth at short time intervals by external gamma counting. The clearance curve was resolved into three phases for each subject--chewing time (1), which coincided with the time to reach 10% of the initial counting rate, scavenging time (2), and a final slow diffusion phase (3). Although the mean chewing time was only 1.9 min, the technique allowed the pattern of clearance during this phase to be assessed for each of 10 normal children (mean age 11.1 yr) and 7 children (mean age 11.0 yr) diagnosed as having delayed articulation. Two measurements of sensory and motor functions of the tongue were made on the same subjects. These measurements were of oral stereognosis and tongue-tip manipulation. Within the control group, only the correlation between stereognosis error scores and the duration of phase 1 or phases 1 and 2 combined was statistically significant. The mean stereognosis and tongue manipulation scores were significantly lower in the poor articulation group than in normal children but, with one notable exception, the clearance curves were similar.

Adolescent↗
PubMed1988

Subjective assessment of liquid volumes by humans during swallowing.

To test the hypothesis that during drinking the appreciation of a volume of fluid in the mouth (VM) is important in determining the volume swallowed (VS), we assessed how well subjects recognized different volumes taken into the mouth and swallowed. Five volumes of tap water (5-25 cm3) were drunk in random order with the eyes closed and the subjects assessed these by selecting from an assortment of cylindrical blocks those with volumes which were thought to correspond visually or manually to the test volumes. Two known reference volumes and cylinders each of 15 cm3 were included in the test. Scores for total error magnitude, correct responses and bias showed that subjective assessment of volumes, though poor, was reproducible and that a student group performed better than children and elderly subjects who consistently underestimated VM. Of the factors studied which might contribute to perception of VM, the time taken for water to enter the mouth, but not the interval before swallowing, seemed most important. Raising the water temperature to 37 degrees C, surface anaesthesia of tongue and palate, and sipping as opposed to gulping, did not alter scores in students. The mean VS in unrestricted drinking was 12.6 cm3 for 44 students; repeat measurements in an individual varied by only about 11 per cent.

Adult↗
PubMed1986

The relationship between fluoride concentrations in serum and in mineralized tissues in the rat.

By means of mini-osmotic pumps implanted into rats (110-240 g body wt), steady-state fluoride levels in serum were raised throughout a 21-day period. Small volumes of a fluoride solution twice daily by gastric intubation produced transient elevations of serum fluoride, base-line values being reached within 6 h. The calculated mean fluoride increments in serum were similar to those observed in the infused rats through the daily dosages of fluoride were about 1.0 and 0.625 mg F/kg respectively. The amounts of fluoride incorporated into periosteal bone, incisor dentine and newly-formed enamel were generally greater in the infused than intubated rats, but these differences were reduced or absent when fluoride concentrations were related to the serum-fluoride concentrations. The results from a few rats given 1.25 mg F/kg per day by continuous infusion confirmed that the amounts of fluoride incorporated into mineralized tissues were closely related to the serum-fluoride levels. Rats were also given these fluoride supplements from the 10th day of pregnancy until parturition. The mode of fluoride administration did not affect the amount of fluoride incorporated into the tissues of the mothers or into the skeletal ash of the pups when the results were expressed in relation to maternal serum-fluoride levels.

Animals↗
PubMed1984

Secretion of saliva by human lip mucous glands and parotid glands in response to gustatory stimuli and chewing.

To test the suggestion that minor salivary glands, such as the lower lip mucous glands, respond to stimulation in a similar manner to major glands such as the parotid, an appliance was constructed for each subject using an organopolysiloxane dental impression material which held a strip of filter paper against the inner aspect of the lower lip. The volume of labial secretion produced was determined by weight difference. Saliva from the right parotid duct was collected into pre-weighed tubes using a Lashley cannula. Test stimuli, applied for 4-min periods in triplicate, were ascorbic acid (0.08 and 0.16 M), sodium chloride (0.4 and 0.8 M) and the chewing of pieces of polyurethane foam and chicle. In 7 of 13 subjects, the response patterns of labial and parotid glands were qualitatively similar. With acid stimulation, the percentage increase in flow from the parotid was much greater than from labial glands. A significant difference was noted between the mean volumes of unstimulated secretion from the lip glands in a group of 8 subjects with restorations in lower anterior teeth and in 12 controls.

Ascorbic Acid↗
PubMed1983

Correlations between the concentrations of fluoride and some other constituents in tea infusions and their possible dental caries-preventive effect.

Tannic acid, total, complexed and ionized fluoride, calcium, total phosphate, zinc, aluminium, copper, iron, mercury and manganese were determined in infusions prepared from some or all of 30 brands of tea. Mercury and copper were not detected. Significant positive correlations were observed between fluoride, aluminium and manganese. The low reactivity of fluoride in tea infusions with powdered hydroxyapatite compared with that in dilute sodium fluoride solutions may be in part explained by the presence of aluminium and manganese.

Aluminum↗