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Biomedical subjects

D Bartlett

Publications and source records attributed to D Bartlett.

At least 37 records · Page 2Linked to original sources
PubMed2001

Respiratory response to baroreceptor stimulation and spontaneous contractions of the urinary bladder.

Spontaneous contractions of the urinary bladder (SBCs) and experimental elevations of carotid sinus pressure (CSP) have been shown to result in respiratory inhibition with preferential reduction in hypoglossal (HG) nerve activity as compared with that of phrenic nerve discharge. We assessed the interaction between these respiratory inhibitory stimuli in decerebrate, vagotomized, paralyzed and artificially ventilated cats. We denervated the right carotid sinus and pressurized the isolated left carotid sinus region within the linear range of the baroreflex, while maintaining systemic arterial pressure at approximately 100 mmHg. We monitored the HG and phrenic nerve responses to SBCs, to elevations in CSP between SBCs, and to elevations in CSP during SBCs. Our results show that superimposing these stimuli results in respiratory inhibition, especially of HG activity, that exceeds that resultant from either stimulus alone. We speculate that the combined presence of SBCs and episodic hypertension may contribute to the development of periodic breathing or obstructive apnea, particularly during sleep.

Animals↗
PubMed2001

Preventative measures for bulimic patients with dental erosion.

The preventative techniques suggested to bulimic patients are frequently undervalued and ignored in favour of restorative treatment, possibly because the dentist may not be aware of the eating disorder. Educating bulimic patients about fluoride application, the use of brushing techniques, antacids, cheese, xylitol chewing gum and the possible use of mouth guards may minimise the effect of acids. Together with attempts at improving patient compliance they can be a valuable adjunct to treatment of bulimic patients with dental problems. Monitoring the wear on teeth by comparing study casts is a good way to maintain control but there are circumstances when restorations are indicated, perhaps when further delay may result in the prognosis of the teeth being compromised. Following a brief introduction to causes of bulimia and the consequences to the dentition, this paper, based on a literature review, considers patient-orientated techniques for prevention and provisional management of erosion of dental hard tissues for patients with bulimia nervosa.

Antacids↗
PubMed2000

Respiratory response to spontaneous contractions of the urinary bladder in awake and decerebrate rats.

Spontaneous contractions of the urinary bladder (SBCs) have been shown to decrease the frequency and depth of respiration in anesthetized or unanesthetized, decerebrate cats. The respiratory responses to bladder voiding reflexes in the awake state have not been previously addressed. Because a chronic rat model for the study of bladder function has been established and breathing measurements can be made in the awake rat, we chose the rat as an experimental model to assess whether SBCs would alter breathing in the conscious, intact animal. Respiratory frequency increased during bladder contractions but tidal volume remained unaffected. To assess whether the respiratory response to bladder reflexes in rats differed from that previously observed in cats, we also studied decerebrate, vagotomized, paralyzed and artificially ventilated rats. Contrary to the respiratory inhibition observed in decerebrate cats, phrenic and hypoglossal nerve activities remained unaffected during SBCs in decerebrate rats. These results indicate a species difference in the coupling between respiration and bladder voiding reflexes.

Animals↗
PubMed2000

European measurements of aircraft crew exposure to cosmic radiation.

For more than 5 y, the European Commission has supported research into scientific and technical aspects of cosmic-ray dosimetry at flight altitudes in civil radiation. This has been in response to legislation to regard exposure of aircraft crew as occupational, following the recommendations of the International Commission on Radiological Protection in Publication 60. The response to increased public interest and concern, and in anticipation of European and national current work, within a total of three multi-national, multi-partner research contracts, is based on a comprehensive approach including measurements with dosimetric and spectrometric instruments during flights, at high-mountain altitudes, and in a high-energy radiation reference field at CERN, as well as cosmic-ray transport calculations. The work involves scientists in the fields of neutron physics, cosmic-ray physics, and general dosimetry. A detailed set of measurements has been obtained by employing a wide range of detectors on several routes, both on subsonic and supersonic aircraft. Many of the measurements were made simultaneously by several instruments allowing the intercomparison of results. This paper presents a brief overview of results obtained. It demonstrates that the knowledge about radiation fields and on exposure data has been substantially consolidated and that the available data provide an adequate basis for dose assessments of aircraft crew, which will be legally required in the European Union after 13 May 2000.

Aircraft↗
PubMed2000

Adapting crown preparations to adhesive materials.

Traditional approaches to crown preparation for replacement crowns or teeth with short clinical crowns are often overly destructive of tooth tissue. Adhesive cements or composites combined with dentine bonding agents provide the clinician with some flexibility in treatment planning and should be considered when more destructive techniques would otherwise be necessary.

Adhesives↗
PubMed1999

Bladder contractions alter inspiratory termination by superior laryngeal and intercostal nerve stimulation.

Gradual distension of the urinary bladder evokes spontaneous bladder contractions (SBCs), which are associated with reduced inspiratory activity in the phrenic and other inspiratory motor nerves. We examined the influence of isovolumetric SBCs on the threshold for termination of phrenic inspiration by electrical stimulation of superior laryngeal and/or mid-thoracic intercostal nerves (ICN) in decerebrate, vagotomized, paralyzed, ventilated cats. Although SBCs reduced phrenic inspiratory activity, the threshold for inspiratory termination by nerve stimulation was increased. The results emphasize the complexity of the synaptic connections among brain stem neurons governing micturition and breathing.

Animals↗
PubMed1999

Effects of experimental cortical seizures on respiratory motor nerve activities in piglets.

Airway obstruction at the level of the larynx causes respiratory insufficiency during experimental seizures in spontaneously breathing, anesthetized piglets (T. E. Terndrup and W. E. Fordyce, Pediatr. Res., 38: 61-66, 1995). To investigate further the neural mechanisms of this obstruction, the activities of the phrenic nerve (PH) and the recurrent laryngeal motor branches to the thyroarytenoid (TA) and posterior cricoarytenoid (PCA) muscles were analyzed in 11 anesthetized, vagotomized, paralyzed, and ventilated piglets. After a control recording period, seizures were induced by subcortical penicillin G injections. Compared with baseline conditions, nerve activities became irregular during seizures. Extraneous TA bursts during PH activation were evident in all piglets during seizures. During ictal phases of seizures, the peak integrated activities of the PH and the expiratory component of the PCA, but not TA or inspiratory PCA activities, were significantly decreased compared with interictal phases. During seizures, a significant delay in the onset of the inspiratory component of PCA activation with respect to the onset of the PH was observed. This study helps to explain respiratory impairment during cortical seizures by providing evidence of impaired timing of activation of laryngeal dilator mechanisms and coordination with those activating the diaphragm. Cyclical PH inhibition during high-intensity cortical discharges may provide a secondary mechanism producing respiratory insufficiency during seizures.

Animals↗
PubMed1999

What the nurse manager can do to avoid an ulcer.

A nurse manager constantly encounters situations that cause stress. Dealing with stress is a function of management. The manager who cannot cope effectively will develop anxiety, which can lead to gastric and peptic ulcers. This article presents strategies for nurse managers to avoid such problems.

Adaptation, Psychological↗
PubMed1998

Hypocalcemic stimulation and nonselective venous sampling for localizing parathyroid adenomas: work in progress.

PURPOSE: To evaluate whether the release of parathyroid hormone (PTH) from parathyroid tumors during selective parathyroid arteriography can help localize the tumors. MATERIALS AND METHODS: In 20 patients (six men, 14 women; age range, 24-72 years) with parathyroid tumors undergoing parathyroid arteriography after failed surgery, serial measurements of PTH were obtained during selective arteriography with nonionic contrast material. PTH levels were measured in the superior vena cava (SVC) before and at varying times from 20 to 120 seconds after arteriography. RESULTS: A 1.4-fold increase in the PTH level of the postarteriographic SVC samples enabled correct prediction of the site of adenoma in 13 of the 20 patients (65%). Of nine patients with positive arteriograms, eight had positive results of postarteriographic sampling. Of 11 patients with negative arteriograms, five had positive results of postarteriographic sampling. CONCLUSION: Sampling the SVC for PTH gradients after selective parathyroid arteriography correctly indicated the site of the adenoma in 13 of 20 patients (65%).

Adenoma↗
PubMed1997

Membrane penetration depth and lipid phase preference of acyl-labeled dansyl phosphatidylcholines in phosphatidylcholine vesicles.

The dansyl fluors of 1-oleoyl-2-[4-(dansyl)amino]butyl]-sn-glycero-3-phosphocholine (18:1,4-dansyl PC) and 1-palmitoyl-2-[1-[(dansyl)amino)]undecanoyl]-sn-glycero-3-phosphoc holine (16:0,11-dansyl PC) were shown to reside at similar depths in phosphatidylcholine vesicles at pH 7. Analysis of fluorescence emission maxima showed that the dansyl groups of both 18:1,4-dansyl PC and 16:0,11-dansyl PC in phosphatidylcholine vesicles experienced environments more polar than methanol, suggesting that the dansyl group attached to the terminus of the undecanoyl chain must fold back toward the bilayer surface. Fluorescence polarization measurements in solid/fluid lipid mixtures show that both probes partition strongly into fluid phase lipid. The very low polarization values of 16:0,11-dansyl PC in lipid vesicles are consistent with the notion that the dansyl fluor of 16:0,11-dansyl PC existed in an environment allowing a high degree of motional freedom due to folding back of the dansyl group attached to the undecanoyl chain.

Dansyl Compounds↗
PubMed1997

Primitive reflexes and the determination of fetal presentation at birth.

Ninety term breech-presenting singletons with birth weights greater than 2500 g and no congenital anomalies were matched with similar cephalic-presenting infants on gender and mode of delivery (n = 180). Thirteen primitive reflexes were examined at birth, 6 weeks and 3 and 5 months. No significant differences in the intensity of the asymmetrical tonic neck, symmetrical tonic neck, positive support tonic labyrinthine (prone and supine), segmental rolling (head-on-body and body-on-body), Galant, Moro, upper and lower extremity grasp, lower extremity placing and stepping reflexes were observed between these two groups of infants. Infants delivered vaginally, regardless of presentation, had weaker Moro reflexes at 5 months than infants delivered by cesarean section. The popular notion that precursors to early motor behaviors, such as the placing and stepping reflexes, are determinants of fetal presentation at the end of pregnancy is not supported by these results. Instead, spontaneously generated active whole body movements may be more significant influences of fetal orientation at the time of birth.

Adult↗
PubMed1997

Roles of the pontine pneumotaxic and micturition centers in respiratory inhibition during bladder contractions.

In decerebrate or anesthetized cats with moderately distended urinary bladders, spontaneous bladder contractions (SBCs) have been shown to decrease phrenic and hypoglossal nerve activities. To determine the involvement of both the pontine micturition center (PMC) and the pneumotaxic center in the respiratory response to SBCs, we recorded phrenic and hypoglossal nerve activities in decerebrate, paralyzed, vagotomized, artificially ventilated cats. Electrical stimulation of the PMC in cats with subthreshold bladder volumes below the threshold for SBCs elicited both increases in intravesical pressure (IVP) and attenuation of respiratory motor nerve activities. Respiration was not altered after PMC lesions, which abolished SBCs, contractions in response to PMC stimulation, and respiratory inhibition due to passive bladder distension. Electrical stimulation of the pneumotaxic center altered respiratory motor nerve activities and increased IVP in cats with subthreshold bladder volumes. Pneumotaxic center lesions caused apneusis, but did not abolish the SBCs, which continued to attenuate the apneustic respiratory motor nerve activity. These results indicate that the PMC is an important component of the reflex pathway from urinary bladder distension to respiratory inhibition, whereas the pneumotaxic center does not appear to be an essential part of this pathway.

Animals↗
PubMed1997

Influence of lung volume on respiratory responses to spontaneous bladder contractions.

Spontaneous bladder contractions (SBCs) in decerebrate, vagotomized, paralyzed, ventilated cats have been shown to decrease phrenic and hypoglossal inspiratory nerve activities, as well as the activities of other respiratory motor nerves. To determine whether vagal afferents from the lung influence the respiratory inhibition associated with SBCs, we recorded phrenic and hypoglossal nerve activities in decerebrate, paralyzed, vagally intact cats. The animals were ventilated by a servo-respirator, which inflated the lungs in accordance with integrated phrenic nerve activity. Maintained increases in end-expiratory lung volume were produced by the application of 2-10 cm H2O positive end-expiratory pressure (PEEP). SBCs were accompanied by decreases in both phrenic and hypoglossal peak integrated nerve activities, as well as by marked decreases in respiratory frequency. The reduction of respiratory frequency was greater with higher levels of PEEP, a few animals becoming apneic during SBCs. After bilateral vagotomy, SBCs continued to decrease phrenic and hypoglossal peak integrated nerve activities as previously reported, but the reduction of respiratory frequency was much less striking than when the vagi were intact. These results indicate that activity of vagal afferents from the lung augments the respiratory influence of SBCs. Furthermore, SBCs in vagally intact animals can induce periodic breathing.

Animals↗
PubMed1997

Primitive reflexes and early motor development.

To investigate the relationship between primitive reflexes and typical early motor development, 156 full-term infants with normal 18-month developmental outcomes were assessed using a modified Primitive Reflex Profile (PRP) and the Alberta Infant Motor Scale (AIMS) at 6 weeks and 3 and 5 months. No significant positive or negative correlations were obtained between the scores of the PRP and the AIMS at any of the ages assessed. Similarly, PRP scores did not differ between infants scoring above and below the 50th percentile on the AIMS. Primitive reflexes were unrelated to motor development. If this finding is maintained among infants at risk for motor disability, observational assessment of spontaneously generated movement, rather than isolated testing of primitive reflexes, might yield more valuable information on the child's overall level of maturation. Intervention for children with identified motor delays or neurological impairments might not need to be focused on either suppression or enhancement of these motor functions.

Developmental Disabilities↗
PubMed1997

Videotaped interviewing of non-English speakers: training for medical students with volunteer clients.

In a multicultural society such as Australia, with over 20% of its population born overseas, interpreters are often required to facilitate medical interviews. However, where a patient has some proficiency in English, medical interviews are sometimes conducted across the boundaries of culture and language. This is a report of an educational innovation to teach interviewing skills to pre-clinical medical students with the assistance of volunteers of non-English-speaking backgrounds. Pre-clinical students interviewed community volunteers on topics of general life history in a sequence of 16 tutorials. Each student conducted two interviews. Teaching methods included feedback from the volunteers, tutorial discussion facilitated by playback of videotapes, and modelling of skills by the teachers. Evaluations by volunteers and students indicated high satisfaction with the teaching methods and outcomes. Students gained confidence in interviewing people from different cultures. Evaluation of students' pairs of videotapes by an independent rater achieved satisfactory reliabilities and indicated significant gains in inquiry skills and the communication of positive attitudes. Skills in communicating empathy and in using simple language did not improve measurably.

Adult↗