Biomedical subjects
R Maxwell
Publications and source records attributed to R Maxwell.
The decision to extract: part II. Analysis of clinicians' stated reasons for extraction.
In a recently reported study, the pretreatment records of each subject in a randomized clinical trial of 148 patients with Class I and Class II malocclusions presenting for orthodontic treatment were evaluated independently by five experienced clinicians (drawn from a panel of 14). The clinicians displayed a higher incidence of agreement with each other than had been expected with respect to the decision as to whether extraction was indicated in each specific case. To improve our understanding of how clinicians made their decisions on whether to extract or not, the records of a subset of 72 subjects randomly selected from the full sample of 148, have now been examined in greater detail. In 21 of these cases, all five clinicians decided to treat without extraction. Among the remaining 51 cases, there were 202 decisions to extract (31 unanimous decision cases and 20 split decision cases). The clinicians cited a total of 469 reasons to support these decisions. Crowding was cited as the first reason in 49% of decisions to extract, followed by incisor protrusion (14%), need for profile correction (8%), Class II severity (5%), and achievement of a stable result (5%). When all the reasons for extraction in each clinician's decision were considered as a group, crowding was cited in 73% of decisions, incisor protrusion in 35%, need for profile correction in 27%, Class II severity in 15% and posttreatment stability in 9%. Tooth size anomalies, midline deviations, reduced growth potential, severity of overjet, maintenance of existing profile, desire to close the bite, periodontal problems, and anticipation of poor cooperation accounted collectively for 12% of the first reasons and were mentioned in 54% of the decisions, implying that these considerations play a consequential, if secondary, role in the decision-making process. All other reasons taken together were mentioned in fewer than 20% of cases. In this sample at least, clinicians focused heavily on appearance-related factors that are qualitatively determinable by physical examination of the surface structures of the face and teeth. They appear to have made primary use of indicators available on study casts and facial photographs and relatively little use of information that is available only on cephalograms or that involves the application of specialized orthodontic theories.
The decision to extract: Part 1--Interclinician agreement.
As part of an ongoing prospective clinical trial of conventional orthodontic treatment, the decision making patterns of a representative group of orthodontic clinicians were examined. Data were available for 148 subjects (100 adolescents and 48 adults) who had presented at the University of California San Francisco Graduate Orthodontic Clinic requesting treatment for correction of a Class I or Class II malocclusion. The records for each subject were evaluated independently by each of five members of the clinical faculty, making available a total of 740 independent patient evaluations. With regard to the primary decision as to whether extraction or nonextraction treatment was to be preferred, agreement among clinicians was higher than had been anticipated. In almost two thirds of the cases, the decisions of all five clinicians were in agreement as to whether extraction or nonextraction was the preferred treatment modality. (This figure included 59 cases of complete agreement for extraction therapy (40%) and 38 cases of complete agreement for nonextraction therapy (26%)). In only 51 cases (34%), did the reviewing clinicians disagree as to whether extraction or nonextraction was the preferred modality of treatment. The clinicians were also asked to indicate their opinions as to whether orthognathic surgery was likely to be a part of the ultimate treatment course for each individual subject. Nine percent of the 740 patient evaluations contained a clinician judgement that surgery would be a probable or definite component of the orthodontic treatment plan. For 29% of the adult subjects (14 cases) and 23% of the adolescent subjects (23 cases), one or more of the five examining clinicians believed that adjunctive surgical intervention would probably or definitely be appropriate. These high values were unexpected, particularly because the sample had been prescreened by a single clinician to exclude subjects who might require orthognathic surgery. Clinician agreement of Angle classification was also evaluated. Disagreements were observed in 14 adult subjects (29%) and 27 adolescent subjects (27%). Little association was observed between clinician agreement on Angle classification and clinician agreement on whether or not to extract.
8-12 Hz rhythmic oscillations in human motor cortex during two-dimensional arm movements: evidence for representation of kinematic parameters.
Direct cortical recordings were taken from 12 patients with implanted subdural electrode arrays during performance of a 2-dimensional, multi-joint, visually guided arm movement task. Task-related changes in the amplitude of the motor cortex 8-12 Hz surface local field oscillations were evaluated for the encoding of direction and amplitude of movement in the 6 patients in whom no epileptogenic or ECoG background abnormalities were detected over the motor-sensory cortical areas under the recording electrode array. The topography, time of onset and duration of these responses were evaluated in the context of motor cortex somatotopy, as defined by cortical stimulation delivered through the electrode array. Multi-joint arm movements were accompanied by a decrease in the power of the 8-12 Hz frequency components of the ECoG signal. These power changes were spatially distributed over the upper extremity, motor-sensory representation. Movement amplitude influenced the magnitude, duration, and extent of the spatial distribution of ECoG power changes in the 8-12 Hz band. These effects occurred predominantly over cortical areas corresponding to the upper extremity motor-sensory representations. Direction of movement had a weaker influence on the 8-12 Hz frequency components of the ECoG over the upper extremity motor-sensory representations, but influenced the patterns of 8-12 Hz ECoG response on adjacent cortical regions. These results show that the amplitude of surface electrical oscillations generated over the rolandic cortex are correlated with the kinematics of multi-joint arm movements. These changes in the ECoG signal appear to reflect shifts in the functional state of neuronal ensembles involved in the initiation and execution of motor tasks.
Effect of chronic thromboembolism on the pulmonary artery pressure-flow relationship in dogs.
To understand the hemodynamic alterations associated with chronic thromboembolic pulmonary hypertension, the large pulmonary arteries of mongrel dogs were chronically obstructed with lysis-resistant thrombi. Pulmonary hemodynamics were experimentally measured and described by multipoint pulmonary arterial pressure (PAP) vs. flow plots. In nine anesthetized chronically embolized dogs, but not in six control dogs, the PAP-flow line shifted significantly upward in a parallel fashion by 4.2 +/- 0.7 mmHg. The postembolic pulmonary circulation was further characterized by predictions from a morphometric-based elastic tube and sheet flow model of the canine pulmonary circulation. After model validation with the preembolic PAP-flow data, the derived postembolic PAP matched the in vivo results to within 1 mmHg. A detailed analysis of the model-derived PAP drop revealed that the PAP-flow line shift can be accounted for by a novel fixed resistor in the largest obstructed pulmonary artery.
Tackling inequalities in health: the Australian experience.
Federal and state governments in Australia have embarked on a series of national initiatives which show a firm commitment to tackling social inequalities in health. The development of national goals and targets for health, for example, covers social and environmental conditions and sets differential targets for specific social groups with very poor health status. In a complementary initiative, a wide ranging analysis of the health care system--the National Health Strategy--has as one of its main objectives to improve the equitable impact of the health system. Where problems of access to and quality of services have been exposed, policies have been devised to deal with them. The exceptionally poor health of the Aboriginal community has elicited cross party support for action. Resources have been allocated to implement the National Aboriginal Health Strategy: to improve living and working conditions, education, and employment opportunities. Britain can glean much from the Australian experience.
Other cities, same problems.
London's health care problems, particularly underfunding, are mirrored in other major cities in the United Kingdom and abroad. None has found the perfect solution, but the debates on the Tomlinson report provide an opportunity to review how to manage the three major areas of service provision, medical education, and research in London. Mr Robert Maxwell suggests that some aspects of the successful ambulatory care initiative in New York could be adapted by the capital's primary care providers while the secondary services might learn from the rationalisation of specialist services in Paris.
Outcome of resective surgery for intractable partial epilepsy guided by subdural electrode arrays.
The aim of this paper was to evaluate the outcome and the factors predictive for a good prognosis of resective surgery for intractable partial epilepsy guided by subdural electrode arrays (SEA's) and operative electrocorticography. Sixty-four patients, aged 8-52 years, were evaluated with chronic SEAs in order to record interictal and ictal activity and delineate speech and motor areas by functionally mapping. Resection were individualized to each patient's SEA recorded electrocorticogram and operative electrocorticogram and functional mapping results (tailored resection). The follow-up time was a minimum of one year. Good seizure outcome was defined as seizure free from complex partial and secondary generalized seizures. After one year 70% of the patients with a temporal ictal focus was seizure free compared to 55% of the patients with an extra-temporal focus. Complete resection of interictal or ictal fields as mapped with SEAs, gave better prognosis than partial resection. Patients with no postresection spikes had a better prognosis than patients with residual postresection spikes evaluated with operative electrocorticography. Sex, age, duration of epilepsy prior to surgery, extent of temporal lobe resection and structural abnormalities determined by MRI were not associated with a favorable seizure outcome after surgery. We conclude that complete resection of the interictal and ictal field mapped with SEA's and absence of postresection spikes on operative electrocorticography are associated with an excellent seizure outcome.
Aneurin Bevan on the NHS.
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Dipolar 31P NMR spectroscopy of crystalline inorganic phosphorus compounds.
The ability of the 90 degrees-t1-180 degrees pulse sequence to produce accurate dipole-dipole coupling information in solids is investigated. To this end, the experimental 31P spin echo decays are measured for eighteen crystalline phosphides and phosphorus chalcogenides and compared with simulations, based on the known internuclear distances in these compounds. The experimental results are generally found accurate in compounds where the dominant contribution to the dipole-dipole coupling arises from nuclei in structurally inequivalent sites with large chemical shift anisotropies. For this situation, the quantum mechanical "flip-flop" term in the dipolar Hamiltonian is suppressed and the dipole-dipole coupling is entirely heteronuclear in character. All of those compounds that do not obey this condition show accelerated spin echo decays due to a fractional contribution of the flip-flop term and possibly incomplete refocusing of chemical shift terms on the time scale of the experiment. The results confirm on an empirical basis that the spin echo NMR technique can provide accurate dipole-dipole coupling information (and thus distance distributions) in disordered solids and glasses.
Shoulder stabilization following traumatic scapulectomy.
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Pancreatic pseudocyst due to fractured pancreas.
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Gatekeepers and goalkeepers: general practice advice to purchasers.
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Vulval reconstruction by free tissue transfer. Case report.
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Dentofacial appearance: a comparison of patient self-assessment techniques.
Self-perceptions of facial appearance are important in patients' willingness to seek treatment. Unfortunately, patients usually only perceive defects of the mandible, making counseling regarding other facial deformities difficult for the orthodontist and oral surgeon. Self-drawings of profile form may be used by orthodontists to determine patients' understanding of their facial defects and to help educate patients about their defects and the need for surgical or other correction. This study of 35 patients seeking orthognathic surgery revealed that patients' self-ratings of their vertical, mandibular, maxillary, and dentoalveolar defects are correlated with some cephalometric measures, as are their self-drawings of the vertical and mandibular dimensions. Therefore, it appears that the two self-assessment techniques may be used simultaneously to illustrate defects on different dimensions. Overall body image and facial image were not associated with cephalometric measures, suggesting that patients' general feelings about their facial appearance are unrelated to their descriptions of their features or to objectively determined defects. However, self-ratings on specific features of the face were correlated with cephalometric measures of nasal height, on both hard and soft tissue dimensions.
Contracts and quality of care.
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Interhemispheric transfer in patients with incomplete section of the corpus callosum. Anatomic verification with magnetic resonance imaging.
Tests of interhemispheric disconnection including visual, somesthetic, kinesthetic, auditory, and complex motor functions were performed on seven patients with chronic epilepsy who had undergone partial surgical section of the corpus callosum, verified by magnetic resonance imaging. Two patients with only one third of the splenium remaining demonstrated disconnection syndromes involving all modalities except vision, which was completely intact. Five patients had lesions involving the rostrum and the anterior two thirds to four fifths of the body of the callosum, with the splenium spared. They demonstrated little evidence of disconnection in the modalities indicated, except for left ear suppression on a dichotic listening task and partial somatosensory disruption in some cases. These results emphasize the importance of the posterior corpus callosum for interhemispheric sensory and sensorimotor transfer, although some discrepancies between current behavioral data and previous anatomic findings remain.
Cerebral distribution of immunoconjugate after treatment for neoplastic meningitis using an intrathecal radiolabeled monoclonal antibody.
A detailed autopsy and autoradiographic study was performed after the death of a patient undergoing intrathecal, antibody-guided irradiation for carcinomatous meningitis. The results demonstrated tumor cells infiltrating the surface meninges and a severe astrocytic reaction associated with oedema in the periventricular and brain stem subpial white matter. This was not seen in cortical or other gray matter structures. Autoradiographic examination correlated well, demonstrating isotope within the oedematous areas of the white matter in addition to the expected concentration in the leptomeningeal layers. These findings are discussed in the context of antibody binding to tumor tissue and the possible benefits conferred in the treatment of infiltrating tumor cells.