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Biomedical subjects

C M Carey

Publications and source records attributed to C M Carey.

At least 19 recordsLinked to original sources
PubMed1998

Composition of plaque and saliva following a sucrose challenge and use of an alpha-tricalcium-phosphate-containing chewing gum.

Calcium phosphate concentrations in plaque, plaque fluid, and saliva play an important role in caries prevention. In this study, we used a microanalytical technique to examine the anticaries potential of a 2.5% (mass fraction) alpha-tricalcium-phosphate-fortified experimental gum by measuring the pH, free and total calcium, and total phosphate in plaque fluid, whole plaque, and saliva, and centrifuged saliva from 14 subjects who (1) accumulated plaque for 48 hours, (2) fasted overnight, (3) rinsed for 1 min with sucrose, and (4) chewed a control or experimental gum for 15 min. From these data, the hydroxyapatite (HAp) ion activity products (IAP[HAp]) of saliva and plaque fluid were calculated as a measure of tooth mineral saturation. Results, compared with those of the control gum, show significant increases in pH and in free calcium and phosphate concentrations in plaque fluid and saliva when the experimental gum was chewed following sucrose ingestion. These increases result in a rise in fluid saturation with respect to tooth mineral that, for plaque fluid, nearly cancels the decrease seen with the control gum after the sucrose rinse. This suggests that the experimental gum may be more effective than a conventional gum in ameliorating the cariogenic effects of sucrose. Similar statistically significant increases were also seen in the total calcium content of the plaque fluid, centrifuged saliva, whole saliva, and whole plaque, and in the total phosphate of whole plaque and whole saliva. These results suggest that the deposition of a mineral reservoir in plaque and saliva by the experimental gum may help resist future cariogenic challenges.

Adult↗
PubMed1997

An in vitro diffusion model for the study of calcification of bovine pericardium tissue.

Bovine pericardium (BP) is extensively used for the production of heart valve bioprostheses. BP has excellent mechanical properties but a limited lifespan because of intrinsic subsurface calcification in vivo. In this study, the in vitro mineralization of BP was investigated by a novel diffusion cell model. In two sets of experiments, glutaraldehyde-treated BP membranes were placed between two compartments, both of which contained calcium phosphate solutions made by equilibration of octacalcium phosphate (Exp I) or dicalcium phosphate dihydrate (Exp II) in phosphoric acid. The movement of calcium (Ca), phosphate (P), and protons through the BP membrane was followed throughout the diffusion process. Histology, scanning electron microscopy, wet chemical analysis, and energy dispersive X-ray analyses provided good evidence of subsurface mineralization of BP that resembled in vivo mineral deposition. Energy dispersive x-ray microanalyses found a Ca/P heterogeneity of the early subsurface mineral that formed in the membrane. The use of a diffusion cell to model BP calcification under well-characterized conditions has led to in vitro mineralization that more closely matches that observed in vivo. The results suggest that this in vitro diffusion model can be used to study the mechanism of pathological mineralization. This model has the potential to provide rapid, inexpensive, basic information about the mineralization process.

Animals↗
PubMed1997

Choroid plexus papilloma and cysts in the Aicardi syndrome: case reports.

Two female infants with callosal agenesis, infantile spasms, chorioretinal lacunae, optic disc colobomas and cortical heterotopias were diagnosed with Aicardi syndrome. A choroid plexus papilloma was found in one patient, and choroid plexus cysts were found in the other. Choroid plexus lesions are common findings in the Aicardi syndrome and are discussed in this paper.

Agenesis of Corpus Callosum↗
PubMed1997

Changes in the permselectivity of human teeth during caries attack.

Previous studies have shown that enamel permselectivity can influence fluid composition within caries lesions during de- and remineralization. The permselectivity of human enamel, cementum, and dentin sections was examined, in a microwell model, by measurement of the membrane potential developed by KCl diffusion while the sections were immersed in solutions simulating resting (pH = 5.6) and cariogenic plaque fluid (pH = 4.8). In a second experiment, the effects of charged compounds (phytate and Zonyl-FSC) on the tooth permselectivity were examined. The average membrane potentials (+/- SD) in "resting plaque" solution were: sound enamel, 18.9 +/- 3.2 mV, n = 66; dentin, 0.9 +/- 9.2 mV, n = 59; and cementum, -0.8 +/- 8.2 mV, n = 42, with a positive sing indicating cation selectivity. The average membrane potentials became more negative in "cariogenic plaque" solution for all types of sections: sound enamel, 5.2 +/- 2.1 mV, n = 46; dentin, -8.1 +/- 7.4 mV, n = 45; and cementum, -14.3 +/- 8.0 mV, n = 34. In lesion enamel sections, the membrane potential was reduced from the non-lesion wells in both types of test solutions, while phytate treatment caused an increase of approximately 10 mV in potential (increased cation selectivity) in every enamel well in either "resting" or "cariogenic" solution. Treatment of enamel sections with Zonyl-FSC caused the membrane potential to become more negative in both test solutions, with many of the wells showing anion selectivity in the cariogenic "plaque-like" solution. However, the changes in enamel membrane potentials induced by Zonyl-FSC slowly increased toward the initial values after treatment, while the effects of the phytate pre-treatment persisted. Most dentin sections treated with phytate also showed an increase in potential after phytate treatment; however, Zonyl-FSC seemed to have little effect on the membrane potential of dentin. The results of this study suggest that modification of tooth permselectivity by surface-active agents may be a viable method of decreasing the rate of caries progression.

Dental Caries↗
PubMed1997

Increased overnight fluoride concentrations in saliva, plaque, and plaque fluid after a novel two-solution rinse.

Recent studies showed that salivary, plaque-fluid, and whole-plaque fluoride were significantly higher 120 min after subjects rinsed with a novel two-solution rinse than after they rinsed with a NaF rinse of the same fluoride concentration. In this study, the persistence of these increases was investigated overnight, a period of time that is more clinically relevant. Improved analytical techniques for the ultramicro determination of whole-plaque and plaque-fluid fluoride from the same sample are also described. Thirteen subjects abstained from toothbrushing for 48 hrs and rinsed for 1 min with a 12 mmol/L (228 ppm) NaF or the two-solution rinse before bedtime. Samples were then collected the following morning before breakfast: (1) Saliva samples were either clarified by centrifugation or acid-extracted with 1 mol/L HClO4; and (2) single-site molar plaque samples were centrifuged to obtain plaque fluid and/or extracted with 1 mol/L HClO4. Results showed that, compared with NaF, the two-solution rinse produced significantly higher fluoride concentrations in all samples: The concentration of fluoride in whole plaque and whole saliva following the new rinse exceeded concentrations found after the NaF rinse by factors of three and four, respectively, while in plaque fluid, the two-solution rinse produced about a two-fold increase over NaF values, which were near baseline levels. This increase, however, was only about 20% in centrifuged saliva. The increases in saliva and especially in plaque-fluid fluoride after the two-solution rinse indicate a greater remineralization potential, while the enhanced fluoride reservoirs found in plaque overnight after this rinse constitute a reserve that may release fluoride into the plaque fluid over an extended period of time.

Adult↗
PubMed1995

Intensive swimming: can it affect your patients' smiles?

Athletes who swim intensively, such as those who swim laps more than six hours a week, may develop unusual yellowish brown or dark brown stains on their teeth. The authors hypothesize that long-term contact of the teeth with swimming pool water, as well as the mixture of oral fluids with swimming pool water, leads to the formation of these deposits. The authors report two cases of development of such stains.

Adolescent↗
PubMed1994

Cyclic polyamine ionophore for use in a dibasic phosphate-selective electrode.

A cyclic polyamine, 3-decyl-1,5,8-triazacyclodecane-2,4-dione (N3-cyclic amine), was used as the ionophore for a dibasic phosphate-selective electrode. This electrode exhibited a linear response between 1.0 mumol/L and 0.1 mol/L dibasic phosphate activity with a near-Nernstian slope of approximately -29 mV per activity decade. The electrode selectivity for dibasic phosphate over other commonly occurring anions was evaluated. A mechanism for the selectivity of the electrode toward HOP4(2-) ions is postulated to be a function of the size and charge of the N3-cyclic amine ionophore relative to the size and charge of HPO4(2-) ions. The electrode's superior selectivity and sensitivity make possible the direct measurement of phosphate activity in a wide variety of applications.

Heterocyclic Compounds↗
PubMed1992

In vivo fluoride concentrations measured for two hours after a NaF or a novel two-solution rinse.

The concentrations of fluoride in various samples from the oral environment were measured at timed intervals after a novel rinse or a NaF rinse, both containing a total of 12 mmol/L (228 ppm) fluoride. The novel rinse consisted of two solutions mixed just before application: Part A contained calcium chloride and sodium acetate; part B contained a hydrolyzable source of fluoride (sodium hexafluorosilicate) and sodium phosphate. Samples were obtained as follows: Single-site plaque-fluid samples were obtained by centrifugation of first-molar plaque; pooled whole-plaque samples were collected from second molars; centrifuged, pooled whole-saliva was collected by vacuum. All samples were analyzed by micro-analytical methods. Results showed that, compared with NaF, the two-solution rinse produced significantly higher salivary fluoride concentrations, plaque-fluid fluoride concentrations, and acid-extractable fluoride in the whole plaque by factors of about 4, 2, and 6, respectively, at 120 min. The results of this study suggest that the new rinse may provide a greater cariostatic effect at the same fluoride dosage than does a NaF rinse.

Adult↗
PubMed1992

Distribution of fluoride in saliva and plaque fluid after a 0.048 mol/L NaF rinse.

An ultramicro method has recently been described for measurement of plaque-fluid fluoride concentration (Vogel et al., 1990a). This method was used: (1) for exploration of the variation in fluoride concentration of plaque fluid collected from the same buccal tooth sites following a 0.048 mol/L NaF (0.2%) rinse, and (2) for examination of the distribution of fluoride in plaque fluid and saliva within one hour after this rinse. Results indicated an average coefficient of variation (CV) of 31% for plaque-fluid fluoride in triplicate samples recovered simultaneously from the buccal-proximal region of two teeth after the rinse. This was similar to the CV found for plaque-fluid fluoride from the same sites after separate administrations of the rinse. A strong linear correlation was found between salivary and plaque-fluid fluoride at 30 and 60 min after rinse administration, showing that plaque-fluid fluoride is influenced by the concentration of salivary fluoride after administration of this rinse. Plaque-fluid fluoride concentrations were higher than that in saliva at baseline, 30, and 60 min. Very large inter-site and intersubject variations in plaque-fluid distribution were observed, with the central incisors showing the slowest clearance. These variations suggest that an examination of plaque-fluid fluoride from specific tooth regions may be essential for understanding the effects of fluoride on the site-specificity of caries.

Adult↗
PubMed1991

Echocardiographic left ventricular wall thickness: a poor predictor of the severity of aortic valve stenosis.

Echocardiographic left ventricular hypertrophy is thought to be helpful in grading the severity of aortic stenosis. This study compared M-mode echocardiographic left ventricular wall dimensions with Gorlin aortic valve area. Good quality echocardiograms were obtained in 294 patients with aortic stenosis who also underwent cardiac catheterization. Patients with grade 3 or 4 aortic regurgitation were excluded. The correlation was calculated between the aortic valve area and the left ventricular wall dimensions. Correlation coefficients were poor; r = 0.13 for the septum, r = 0.15 for the posterior wall, and r = 0.17 for the mean wall dimension. Correlation was not improved significantly if patients with poor left ventricular function or systemic hypertension were excluded. Correlation with other hemodynamic parameters was better, peak left ventricular systolic pressure having r values of 0.36 and 0.30 for posterior wall and septum. Mean and peak aortic valve gradient had r values approaching 0.30 for both dimensions. If the peak gradient was included in multivariate analysis, the wall dimensions then had no predictive power for severity of aortic stenosis. This study demonstrates that the degree of left ventricular wall hypertrophy is not related to the severity of aortic outflow obstruction and therefore cannot be used to grade the severity of aortic stenosis.

Aortic Valve↗
PubMed1991

Permselectivity of sound and carious human dental enamel as measured by membrane potential.

A microwell technique was used for determination of the permselectivities of sound and carious enamel in the same slice of tooth. The permselectivity determination was accomplished by drilling microwells in the enamel and filling them with a simulated plaque fluid containing lactate, carbonate, and inorganic ions at concentrations similar to those in resting plaque fluid, but with different concentrations of KCl. The electrical potentials developed across the enamel membrane were measured with microreference electrodes placed in the wells or in the solution outside the tooth. The results showed that the membrane potential was a function of the composition of the solutions separated by the enamel membrane and was independent of the composition of the solutions in the adjacent wells. The enamel was found to be cation-permselective, and sound enamel was more permselective than carious enamel. The flux rate of K+ was estimated from the change in the K+ concentration of the well solution as a function of time. The flux rate and the membrane potential data were used in the Nernst-Planck Flux Equation for calculation of the diffusion coefficient of K+ through enamel. The results indicate that the permselectivity of enamel can greatly influence the diffusion of ions through enamel membranes.

Carbonic Acid↗
PubMed1990

Micro-analysis of plaque fluid from single-site fasted plaque.

Despite the site-specific nature of caries, nearly all data on the concentration of ions relevant to the level of saturation of plaque fluid with respect to calcium phosphate minerals or enamel are from studies that used pooled samples. A procedure is described for the collection and analysis of inorganic ions relevant to these saturation levels in plaque fluid samples collected from a single surface on a single tooth. Various methods for examining data obtained by this procedure are described, and a mathematical procedure employing potential plots is recommended.

Colorimetry↗
PubMed1990

Fluoride analysis in nanoliter- and microliter-size fluid samples.

A variety of techniques is described for measuring fluoride in volumes of from 0.005 to 5 microL, including: (1) micropipette procedures for transference and dilution of samples, (2) construction of miniature and micro fluoride-selective electrodes, and (3) methods for adapting standard electrodes for micro- and semi-micro volumes. These described techniques have a number of advantages, including speed of analysis, high accuracy, and adaptability to many types of fluid samples. Recent studies involving use of these procedures include the analysis of fluoride in: (1) plaque fluid samples from single sites before and after topical fluoride administration, (2) tooth mineral samples recovered by acid-etch or microdrill biopsy of enamel, and (3) fluid recovered from the interior of the tooth during simulation of the caries process.

Dental Enamel↗
PubMed1988

The buffer capacity of single-site, resting, human dental-plaque fluid.

A carbonate equilibration method was used to measure the buffer capacity of resting plaque fluid collected from single buccal or interproximal sites of upper and lower first molars or anterior teeth. The maximum buffer capacity was 26 m-equiv./l at pH 7.1. The buffer contribution from the measured concentrations of phosphate and carbonate was calculated for each sample. These values were compared with the buffering actually measured and with that expected from organic acids, proteins, and amino acids at average values, as taken from reports in the literature. Relative contributions of buffer species at the average pH of the samples (6.86) were: 35 per cent phosphate, 10 per cent carbonate, 10 per cent protein, 10 per cent organic acids, 2 per cent amino acids, 30 per cent unidentified. There were no significant differences in the buffer capacities of samples originating from sites that differ in their accessibility to saliva. Buffering in resting plaque fluid is more than twice that in saliva and did not show differences correlated with the intra-oral location of the samples.

Buffers↗
PubMed1988

Extracellular potassium concentrations in human dental plaque fluid recovered from single sites.

Previous studies using potassium ion-selective microelectrodes have demonstrated that potassium concentrations in dental plaque fluid obtained by centrifugation are identical to whole plaque values determined immediately after collection. Such procedures were now used to examine the variations in potassium concentrations between single-site samples of overnight-fasted resting plaque fluid. The potassium concentrations (67.3 +/- 10.8 mmol/l, N = 50) were similar to those found before in whole plaque within 1 min of removal from the mouth and did not appear to be site-dependent. Possible mechanisms for the maintenance of potassium in plaque fluid at higher than salivary levels are described.

Dental Plaque↗
PubMed1988

The determination of extracellular fluid volume in whole dental plaque using potassium- or chloride-selective micro-electrodes.

This paper describes a procedure for the determination of the volume of water available for diffusion in whole plaque samples collected from single sites. In this procedure, known micro volumes of H2O were added to single-site plaque samples with calibrated nanoliter pipettes and the potassium or chloride concentration at each dilution measured with ion-selective micro-electrodes. By plotting the inverse of the concentration versus the volume of H2O added, one can determine the original volume of plaque fluid available for diffusion. Volumes determined in simultaneous measurements performed with chloride and potassium micro-electrodes were statistically indistinguishable. From the observed constancy in the initial potassium concentration in rat and human plaque fluid, a simplified macro method is suggested which allows for estimation of the extracellular fluid volume within 20% error in plaque samples.

Animals↗
PubMed1988

Micro-analysis of mineral saturation within enamel during lactic acid demineralization.

In this study, the physicochemical factors responsible for caries-like lesion propagation were investigated by means of a micro-analytical system used to study the fluid within a lesion during a simulation of the decay process. Four 500-microns-thick serial sections prepared from a single human molar were mounted between glass plates with only the natural surface of the tooth exposed. Microwells were then drilled into sound and pre-existing carious regions of the section through one of the plates. These microwells were then filled with fluid under mineral oil, and after a week of equilibration, the natural surface of the section was exposed to a lesion-producing fluid. The concentrations of calcium, phosphate, and hydrogen ions of the fluid in the wells were then followed as a function of time as the lesion advanced. The results of this study, in which lactic acid was used to demineralize enamel, were consistent with those previously reported (Vogel et al., 1987a): The solution within the lesion remained saturated during the acid attack. Differences in initial mobilities of the calcium and phosphate and other ions, a result of the permselectivity of the enamel, increased the concentrations within the lesion and permanently changed the ratio of these ions in the lesion solution. Based on these results, we suggest that the ionic permselectivity of tooth enamel can have a profound effect on the transport of mineral from a caries lesion.

Calcium↗