Biomedical subjects
Publications and source records attributed to P J Nolan.
Webinars on the revisions to ISO 11607, Packaging for Terminally Sterilised Medical Devices, have prompted many questions from manufacturers and package engineers concerned with validating their packaging under the new requirements. A selection of those questions are reviewed here.
The angular-momentum induced transition from a deformed state of collective rotation to a noncollective configuration has been studied. In 157Er this transition manifests itself as favored band termination near I=45 Planck's. The feeding of these band terminating states has been investigated for the first time using the Gammasphere spectrometer. Many weakly populated states lying at high excitation energy that decay into these special states have been discovered. Cranked Nilsson-Strutinsky calculations suggest that these states arise from weakly collective "core-breaking" configurations.
The latest generation gamma-ray detection system, GAMMASPHERE, coupled with the Microball charged-particle detector, has made possible a new class of nuclear lifetime measurement. For the first time differential lifetime measurements free from common systematic errors for over 15 different nuclei ( >30 rotational bands in various isotopes of Ce, Pr, Nd, Pm, and Sm) have been extracted at high spin within a single experiment. This comprehensive study establishes the effective single-particle transition quadrupole moments in the A approximately 135 light rare-earth region. Detailed comparisons are made with theoretical calculations using the self-consistent cranked mean-field theory which convincingly demonstrates the validity of the additivity of single-particle quadrupole moments in this mass region.
We sought to test the hypothesis that laryngeal adductor and cardiac vagal motor neurones respond similarly to the activation of certain afferent inputs. Experiments were performed on a working heart-brainstem preparation of rat devoid of pulmonary stretch receptor feedback. Upper airway negative pressure receptors (UANPR), peripheral arterial chemoreceptors and receptors at the junction of the pharynx and oesophagus were stimulated selectively while recording heart rate, recurrent laryngeal, phrenic and hypoglossal motor outflows, subglottic pressure during constant translaryngeal airflow (as an index of laryngeal resistance), and single unit respiratory neurone activity. Stimulation of all three receptor types produced bradycardia, evoked discharges in the recurrent laryngeal and hypoglossal motor outflows during the post-inspiratory period and caused swallowing. Stimulation of pharyngoesophageal receptors and peripheral chemoreceptors evoked an increase in laryngeal resistance during the post-inspiratory phase indicative of laryngeal adductor motoneurone activation. Although this reflex response cannot be evaluated during UANPR stimulation, some post-inspiratory neurones were powerfully activated suggesting that UANPR probably drive laryngeal adductor muscles. Our data show that motor outflows controlling cardiac rate and laryngeal patency are concurrently activated by these sensory inputs. This may constitute the basis for a stereotyped defensive reflex response which maintains end expiratory lung volume, thus conserving oxygen in conditions of upper airway obstruction. Our observations lend further support to models of cardiorespiratory control which propose close coupling and shared central mechanisms for the regulation of the cardiovascular and respiratory systems.
Spectral compression of the electromyographic (EMG) signal, due largely to decreasing muscle fiber conduction velocity, is commonly used as an indication of muscle fatigue. Current methods of estimating conduction velocity using characteristic frequencies such as the median frequency of the power spectrum, are based on an assumption of uniform spectral compression. To examine changes in the EMG frequency spectrum during fatigue, muscle fiber conduction velocity was measured during sustained, isometric contractions of the biceps brachii. Compression of the EMG power and amplitude spectra was simultaneously examined using the median frequency and an alternative method-the spectral distribution technique. The spectral distribution technique consistently gave a better estimate of the relative change in muscle fiber conduction velocity than either of the median frequencies. This was further examined using a physiologically based EMG simulation model, which confirmed these findings. The model indicated that firing statistics can significantly influence spectral compression, particularly the behavior of characteristic frequencies in the vicinity of the firing rates. The relative change in the median frequency, whether of the amplitude or frequency spectrum, was consistently greater than the relative change in conduction velocity. The most accurate indication of the relative change in conduction velocity was obtained by calculating the mean shift in the midfrequency region of the EMG amplitude spectrum using the spectral distribution technique.
We report a family with Noonan syndrome (NS), giant proximal nerve hypertrophy, and hereditary motor sensory neuropathy type 1A (HMSN1A). Five members of a family were found to have clinical features of NS. In all cases, NS was associated with giant hypertrophy of proximal nerves and two individuals also exhibited café-au-lait spots. In one case, an 8-to-10-cm diameter pelvic mass was shown to be a grossly hypertrophied nerve, with histologic features of demyelination and remyelination. In addition, four of five family members affected with NS were found to have HMSN1A clinically and by demonstration of constitutional HMSN1A duplication on DNA testing. Linkage analysis for NS ruled out the involvement of the neurofibromatosis type 1 gene and the known NS locus in chromosome 12, supporting the existence of an additional NS locus.
METHODS: A double-blind, randomized, placebo controlled trial of the efficacy of flumazenil was conducted in 22 consecutive patients admitted for bronchoscopy. Sedation was induced by individually titrated amounts of intravenous diazepam (mean +/- s.d., 15.75 +/- 4.4 mg). Post bronchoscopy, patients received up to 1 mg of the benzodiazepine antagonist flumazenil (Anexate) or placebo intravenously. Clinical scores for the degree of sedation, orientation in time and space, co-operation and anterograde amnesia were used. These, together with three psychometric tests were performed twice prior to bronchoscopy and on eight occasions in the following 24 h. The psychometric tests were: Tapping Test (TT), Simple Reaction Time (SRT) and Critical Flicker Fusion (CFF) and these were carried out using the automated Multipsy test system. RESULTS: The level of co-operation, orientation in time and space and anterograde amnesia were similar in both groups pre-and-post procedure. However compared with the pre-bronchoscopy assessment, the maximum degree of apparent sedation was significantly less in the flumazenil group in the first 4 h. In support of this, the patients in the flumazenil group also showed a significantly greater proficiency with the TT and CFF test post bronchoscopy (P < 0.05). There was no difference in the incidence of side effects and flumazenil was well tolerated. CONCLUSIONS: In this highly controlled setting, the use of flumazenil (Anexate) was shown to be safe and effective in aiding recovery from benzodiazepine facilitated bronchoscopy and as such provides an additional level of safety for this procedure.
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Mineralocorticoid receptors in the inner medullary collecting duct (IMCD) are protected from glucocorticoid binding by an enzyme, 11 beta-hydroxysteroid dehydrogenase type 2 (11 beta-HSD2). To study the role of 11 beta-HSD2 in acid-base homeostasis, 11 beta-HSD2 activity was measured in rat IMCD-enriched cell suspensions. Homogenates of cell suspensions were incubated in buffers ranging in pH from 6.00 to 8.15 in the presence of 1 microCi of 3H-corticosterone (CS) and 400 microM NAD+. Enzyme activity was expressed as the amount of 3H-CS converted to 3H-11-dehydrocorticosterone (DHCS). IMCD 11 beta-HSD2 activity at pH 6.5 was 49% of activity at pH 7.5; 22.5 versus 11.0 fmol/microgram of protein per h. Experiments also were performed on intact cell suspensions at pH 7.5 and 6.5. There was a 42% inhibition in the IMCD cell suspension conversion rate of 3H-CS to 3H-11-DHCS at pH 6.5; 13.1 versus 7.6 fmol/microgram per h (P < 0.005). In cell suspensions at pH 7.5, 1-day acid loading caused a 26% inhibition in conversion rate, 13.2 versus 9.9 fmol/microgram per h (P < 0.05), when compared with controls. These results suggest that during acute metabolic acidosis, IMCD 11 beta-HSD2 is inhibited and may allow access to the mineralocorticoid receptors by glucocorticoids.
In this study, we set out to determine if home intravenous (i.v.) antibiotic therapy in adult patients with cystic fibrosis (CF) is a feasible, effective and less costly alternative to hospitalization, and to assess the impact of home therapy on quality of life. The study was a prospective, randomized, two-factor mixed design involving adults presenting with respiratory exacerbations of CF. Patients were randomized such that they were discharged home after 2-4 days, or remained in hospital. Seventeen patients had 31 admissions (13 home and 18 hospital). Following 10 days of therapy, there were no significant differences between home or hospital arms with respect to body weight, 12 minute walking distance, sputum weight, pulse oximetry, or improvement in lung function (forced expiratory volume in one second (FEV1), or forced vital capacity (FVC)). Patients who remained in hospital were less fatigued and noted a greater degree of mastery. Patients discharged early noted less disruption to their family life, personal life and sleeping pattern. The total cost for the home therapy arm was approximately half that of the hospital therapy arm. Home intravenous antibiotic therapy in patients with cystic fibrosis was a feasible, cost-effective alternative to receiving therapy in hospital. Although there was no clinical compromise associated with home therapy, there were advantages and disadvantages in terms of quality of life.
The aim of this study was to develop a method of studying the effects of mandibular advancement on oropharyngeal airway dimensions in the sagittal plane in conscious, supine patients. Six white, dentate, male patients with proven obstructive sleep apnoea had sagittal fluoroscopic recordings taken in the resting supine position. Images were recorded at four frames per second as the mandible was advanced with the teeth in contact to maximum protrusion and then opened. Software in the fluoroscopic imaging system permitted measurement of the change in mandibular position together with oropharyngeal airway dimensions expressed as the narrowest dimension observable in the post-palatal and post-lingual sites. Plotting of airway dimensions during mandibular advancement enabled estimation of the degree of protrusion associated with maximal airway benefits. Progressive mandibular advancement produced variable adaptive changes in the post-palatal and post-lingual regions of the oropharynx. The amount of airway opening appeared to be related to the horizontal and vertical relationships of the face and to the dimensions of the soft palate. The changes in post-palatal and post-lingual airway dimensions were not always identical, despite the observation that both tongue and soft palate were seen to move in unison, with close contact being maintained between the two structures. Jaw opening resulted in synchronous posterior movement of both tongue and soft palate, with consequent narrowing of oropharyngeal airspace. Fluoroscopy is a simple method of assessing upper airway changes with mandibular advancement in the conscious patient. The technique should facilitate the selection of subjects for whom mandibular advancement would seem advantageous. The nature of the adaptive response is dependent on individual structural variation. It is suggested that, where artificial mandibular advancement with dental devices is considered beneficial, jaw opening should be kept to a minimum.
Obstructive sleep apnoea may present with a wide range of symptoms resulting in a variety of referral pathways. A multidisciplinary approach to examination and diagnosis helps to determine the most appropriate treatment plan for each individual. The subject is seen by each member of the team, appropriate investigations undertaken and a further meeting arranged at which all opinions are discussed. A reasoned treatment regime is produced, taking into consideration the patient's wishes and overall medical condition. This paper describes the team approach currently employed in the Department of Thoracic Medicine at The Prince Charles Hospital, Brisbane, Australia. The thoracic physician and ENT surgeon work in close collaboration with their dental colleagues: an orthodontist, prosthodontist and a maxillofacial surgeon. An outline of the examination and investigations made by each is described and the multidisciplinary approach is illustrated by a description of the management of five subjects with suspected obstructive sleep apnoea.
Obstructive sleep apnoea may present with a wide range of symptoms resulting in a variety of referral pathways. A multidisciplinary approach to examination and diagnosis helps to determine the most appropriate treatment plan for each individual. The subject is seen by each member of the team, appropriate investigations undertaken and a further meeting arranged at which all opinions are discussed. A reasoned treatment regime is produced, taking into consideration the patient's wishes and overall medical condition. This paper describes the team approach currently employed in the Department of Thoracic Medicine at The Prince Charles Hospital, Brisbane, Australia. The thoracic physician and ENT surgeon work in close collaboration with their dental colleagues: an orthodontist, prosthodontist and a maxillofacial surgeon. An outline of the examination and investigations made by each is described and the multidisciplinary approach is illustrated by a description of the management of five subjects with suspected obstructive sleep apnoea.
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Fourteen temporomandibular joints in seven dry skulls, representing the distribution of horizontal and vertical condylar axis inclinations of a larger population, were imaged with three tomographic projection techniques. Closest anterior and posterior joint spaces were measured on radiographs, and sectioned plaster casts were made from impressions of actual joint space, Individualized horizontal and vertical correction of the condylar axis produced significantly more accurate (p less than 0.005) measures of condylar space than either standard 20-degree horizontal correction (SHC) or individualized horizontal correction (IHC) of the axis. Representations of joint space by SHC and IHC were not significantly different from each other. Numbers of uninterpretable images displayed a similar pattern of 9.5% for individualized horizontal and vertical correction, 14% for IHC, and 17% for SHC. This study supports the use of fully individualized condylar axis correction with temporomandibular joint tomography for increased accuracy of visualization of the osseous anatomy of the joint.
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Ninety-seven traumatized patients had blood samples taken immediately upon admission before any resuscitation. Microaggregate (MA) formation was measured by the screen filtration pressure (SFP) technique. Plasma fibronectin levels (Fn) were measured by immunoturbimetric assay. An Injury Severity Score (ISS) was calculated for each patient. The results show a highly significant correlation between severity of trauma, amount of MA formation, and amount of Fn depletion. We conclude that the highly significant correlation between MA formation and Fn depletion following trauma suggests a role for the reticuloendothelial system (RES) in the clearance of MA that form following trauma. Further, enhancement of RES clearance of MA may be possible by purified Fn or cryoprecipitate administration early in the treatment of trauma patients, thereby preventing the adverse sequelae of end organ MA deposition.