Biomedical subjects
Publications and source records attributed to D Bartlett.
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OBJECTIVE: Sodium hexametaphosphate (SHMP) is a widely used industrial preservative commonly found in children's drinks. In this paper we examined the effect of SHMP incorporated into children's drinks on acid production by the oral biofilm by monitoring salivary concentrations of lactic acid. MATERIALS AND METHOD: Twelve healthy adult subjects with an average age 36 years (range 26-54 years) consumed 10 ml from four children's beverages (Coca Cola and three types of Sunny Delight supplemented with SHMP) and a standard solution of sucrose. Saliva was collected at intervals following exposure of the oral biofilm to the drinks and the clearance of carbohydrates and the appearance of lactate was measured using standard enzymatic techniques. RESULTS: All the carbohydrates derived from the drinks were cleared from saliva within 15 min of consumption. Comparison of two drinks [Sunny D Normal and Sunny C] with the same carbohydrate, but different SHMP concentrations suggested that SHMP in these beverages had no significant effect on acid production. CONCLUSIONS: In this clinical study the role of SHMP, incorporated in common beverages, did not inhibit acid production from carbohydrates.
The laryngeal chemoreflex (LCR), elicited by a drop of water in the larynx, is exaggerated by mild hyperthermia (body temperature = 40-41 degrees C) in neonatal piglets. We tested the hypothesis that thermal prolongation of the LCR results from heating the nucleus of the solitary tract (NTS), where laryngeal afferents first form synapses in the brain stem. Three- to 13-day-old piglets were decerebrated and vagotomized and studied without anesthesia while paralyzed and ventilated. Phrenic nerve activity and rectal temperature were recorded. A thermode was placed in the medulla, and the brain tissue temperature was recorded with a thermistor approximately 1 mm from the tip of the thermode. When the thermode was inserted into the brain stem, respiratory activity was arrested or greatly distorted in eight animals. However, the thermode was inserted in nine animals without disrupting respiratory activity, and in these animals, warming the medullary thermode (thermistor temperature = 40-41 degrees C) while holding rectal temperature constant reversibly exaggerated the LCR. The caudal raphé was warmed focally by approximately 2 degrees C in four additional animals; this did not alter the duration of the LCR in these animals. Thermodes placed in the NTS did not disrupt respiratory activity, but they did prolong the LCR when warmed. Thermodes that were placed deep to the NTS in the region of the nucleus ambiguus disrupted respiratory activity, which precluded any analysis of the LCR. We conclude that prolongation of the laryngeal chemoreflex by whole body hyperthermia originates from the elevation of brain tissue temperature within in the NTS.
EVIDOS is an EC sponsored project that aims at an evaluation and improvement of radiation protection dosimetry in mixed neutron/photon fields. This is performed through spectrometric and dosimetric investigations during different measurement campaigns in representative workplaces of the nuclear industry. The performance of routine and, in particular, novel personal dosemeters and survey instruments is tested in selected workplace fields. Reference values for the dose equivalent quantities, H(*)(10) and H(p)(10) and the effective dose E, are determined using different spectrometers that provide the energy distribution of the neutron fluence and using newly developed devices that determine the energy and directional distribution of the neutron fluence. The EVIDOS project has passed the mid-term, and three measurement campaigns have been performed. This paper will give an overview and some new results from the third campaign that was held in Mol (Belgium), around the research reactor VENUS and in the MOX producing plant of Belgonucléaire.
This work describes spectral distributions of neutrons obtained as function of energy and direction at four workplace fields at the Krümmel reactor in Germany. Values of personal dose equivalent H(p)(10) and effective dose E are determined for different directions of a person's orientation in these fields and readings of personal neutron dosemeters--especially electronic dosemeters--are discussed with respect to H(p)(10) and E.
Heat stress and the laryngeal chemoreflex (LCR) have both been implicated as possible contributors to the sudden infant death syndrome (SIDS). We recently reported that moderate hyperthermia, induced in decerebrate piglets by external heating, substantially prolonged the LCR elicited by injecting 0.1 ml of water into the larynx through a prepositioned transnasal catheter. To examine the question of whether hyperthermia influences the responses of laryngeal water receptors, we recorded single fiber action potentials in fine strands of the superior laryngeal nerve (SLN) in decerebrate piglets while the larynx was filled with water or isotonic saline. Water receptors, identified by their much brisker response to water than to saline, were studied with body temperature at 37.9+/-0.2 degrees C, after warming the animal to 40.6+/-0.2 degrees C and after cooling back to 37.7+/-0.3 degrees C. The results show no effect of body temperature change, in this range, on the responses of the laryngeal water receptors and thus suggest that the potentiation of the LCR by hyperthermia is mediated by a central action.
The topic of occlusion presents a conundrum to many practitioners. To some the topic is very complex and yet to others, although important, it illustrates how adaptive the dentition is to change. This commentary presents some arguments as to how the importance of occlusion and its understanding have evolved since the Journal of Oral Rehabilitation was first published.
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Regurgitated acid entering the mouth in gastro-esophageal reflux disease can cause dental erosion. Chewing gum could induce increased swallowing frequency, thus improving the clearance rate of reflux within the esophagus. The null hypothesis of this study was that chewing gum does not have any effect on the clearance of reflux from the distal esophagus. Thirty-one subjects presenting with symptoms of reflux were given a refluxogenic meal twice and were randomly selected to chew gum for half an hour after eating the meal. Esophageal pH was measured, and pH data were analyzed and compared during the postprandial periods for 2 hrs on the 2 occasions. The median (IQ range) values for the % time pH < 4 during the postprandial period without chewing gum were 5.7 (1.7-13.5) and, with chewing gum, 3.6 (0.3-7.3), respectively (p = 0.001). Chewing sugar-free gum for half an hour after a meal can reduce acidic postprandial esophageal reflux.
Early detection of pancreatic cancer might improve clinical outcome. Significant alterations in the levels of individual serum cytokines have been reported in pancreatic cancer. We hypothesized that a multicytokine panel could serve as biomarkers for pancreatic cancer. To evaluate the diagnostic utility of such a panel, we have utilized a novel multianalyte LabMAP profiling technology that allows simultaneous measurement of multiple markers. In this study, a panel of 31 serological markers including cytokines, chemokines, growth and angiogenic factors in combination with CA 19-9 was analyzed in sera of pancreatic cancer patients, patients with chronic pancreatitis, and matched control healthy subjects. Statistical analysis identified a multicytokine panel that was able to distinguish pancreatic cancer from healthy controls with a sensitivity of 85.7% and specificity of 92.3%, which was superior to performance of CA 19-9 alone. Importantly, a multicytokine panel allowed the discrimination of pancreatic cancer from chronic pancreatitis with high sensitivity of 98% and specificity of 96.4%. In conclusion, we demonstrated that analysis of multiple serum cytokines using a novel LabMAP technology is a promising approach for development of a diagnostic assay for pancreatic cancer.
Hyperthermia and reflex apnea may both contribute to sudden infant death syndrome (SIDS). Therefore, we investigated the effect of increased body temperature on the inhibition of breathing produced by water injected into the larynx, which elicits the laryngeal chemoreflex (LCR). We studied decerebrated, vagotomized, neonatal piglets aged 3-15 days. Blood pressure, end-tidal CO(2), body temperature, and phrenic nerve activity were recorded. To elicit the LCR, we infused 0.1 ml of distilled water through a polyethylene tube passed through the nose and positioned just rostral to the larynx. Three to five LCR trials were performed with the piglet at normal body temperature. The animal's core body temperature was raised by approximately 2.5 degrees C, and three to five LCR trials were performed before the animal was cooled, and three to five LCR trials were repeated. The respiratory inhibition associated with the LCR was substantially prolonged when body temperature was elevated. Thus elevated body temperature may contribute to the pathogenesis of SIDS by increasing the inhibitory effects of the LCR.
Owing to their professional activity, flight crews may receive a dose of some millisieverts within a year; airline passengers may also be concerned. The effective dose is to be estimated using various experimental and calculation tools. The European project DOSMAX (Dosimetry of Aircrew Exposure during Solar Maximum) was initiated in 2000 extending to 2004 to complete studies over the current solar cycle during the solar maximum phase. To compare various dosemeters in real conditions simultaneously in the same radiation field, an intercomparison was organised aboard a Paris-Tokyo round-trip flight. Both passive and active detectors were used. Good agreement was observed for instruments determining the different components of the radiation field; the mean ambient dose equivalent for the round trip was 129 +/- 10 microSv. The agreement of values obtained for the total dose obtained by measurements and by calculations is very satisfying.
EVIDOS ('evaluation of individual dosimetry in mixed neutron and photon radiation fields') is an European Commission (EC)-sponsored project that aims at a significant improvement of radiation protection dosimetry in mixed neutron/photon fields via spectrometric and dosimetric investigations in representative workplaces of the nuclear industry. In particular, new spectrometry methods are developed that provide the energy and direction distribution of the neutron fluence from which the reference dosimetric quantities are derived and compared to the readings of dosemeters. The final results of the project will be a comprehensive set of spectrometric and dosimetric data for the workplaces and an analysis of the performance of dosemeters, including novel electronic dosemeters. This paper gives an overview of the project and focuses on the results from measurements performed in calibration fields with broad energy distributions (simulated workplace fields) and on the first results from workplaces in the nuclear industry, inside a boiling water reactor and around a spent fuel transport cask.
Dentine bonding resins may play a role in protecting dentine against acids for patients with erosion. Therefore, it is important to try and understand what potential difficulties may ensue when bonding to worn dentine. This paper reviews the literature on the changes between normal and worn dentine and the effect of this on the bonding to composite resins. A medline search was undertaken using the terms erosion, tooth wear and dentine bonding up until the spring of 2003. Although there are changes on the surface of worn dentine, there is little evidence that this may affect the bond.
Manifestations of atypical gastroesophageal reflux disease (GORD) are varied, and the presentation of atypical symptoms may occur in the absence of typical symptoms. The most sensitive and specific investigation for GORD is pH monitoring, and its application in atypical disease is utilized throughout this paper as a basis for correlating disease and pathogenesis. The less well-known areas of laryngeal manifestations, particularly chronic hoarseness and globus, are discussed in addition to recent work on orodental manifestations. Well-known areas of cardiac and respiratory manifestations, which include chronic cough and asthma, are also reviewed. Evidence from clinical trials indicates that aggressive anti-reflux therapy in patients with atypical symptoms can be effective. Where appropriate, medical therapy may involve long-term proton pump inhibitor, although further research outlining the roles of other therapies such as surgery is awaited.
Rhythmic contractions of the detrusor muscle, induced by gradual filling of the urinary bladder in decerebrate or anesthetized cats, are accompanied by decreased inspiratory activity in motor nerves to respiratory muscles, particularly those of the upper airway. We have examined the influence of hypercapnia and hypocapnia on these contractions and the accompanying activities of the phrenic and hypoglossal nerves in decerebrate, vagotomized, paralyzed and ventilated cats, some of which had denervated carotid chemoreceptors. Hypercapnia slowed, and then reversibly abolished bladder contractions in most animals, regardless of the state of the carotid chemoreceptors. Bladder contractions were well maintained in progressive hypocapnia, even at end-tidal CO(2) levels below the 'apneic' thresholds of the hypoglossal and phrenic activities. The reductions of the nerve activities in response to bladder contractions were not significantly altered by hypercapnia or hypocapnia. The abolition of bladder contractions by hypercapnia is unlikely to reflect a direct effect of CO(2) or H+ ion on the contractile mechanism of the detrusor muscle, but may be based on inhibition of stretch receptors in the bladder wall and/or an effect of CO(2) or H+ in or near the micturition centers in the brain stem.
Since stimuli from abdominal or pelvic viscera can affect respiratory muscle function, we hypothesized that mechanical stimulation of the gallbladder would result in inhibition of motor activity to the diaphragm and to upper airway muscles. We studied 12 decerebrate, vagotomized, paralyzed, artificially ventilated cats and recorded hypoglossal (HG) and phrenic (PHR) nerve activities while applying 600-1000 g of traction on the gallbladder during four respiratory cycles. Traction resulted in an initial reduction of PHR activity to 87.6+/-15.0% (mean+/-S.D.% of its baseline value), a reduction of HG activity to 74.2+/-27.5% and a lengthening of expiratory time to 178.8+/-81.0%. Subsequently, PHR activity and expiratory time returned toward control values, while HG remained diminished, at 66.4+/-19.1%. Our results show that mechanical stimulation of the gallbladder results in a respiratory inhibition with a disproportionate reduction in HG activity relative to PHR discharge. We speculate that gallbladder stimulation by contractions or surgery may compromise breathing by inhibition of phrenic discharge and upper airway obstruction.