Biomedical subjects
Publications and source records attributed to J T Sharp.
This article describes the various functional achievements attained by the normal child in his progress toward upright walking. The average ages at which such motor accomplishments occur are considered along with their normal time of appearance.
Anteroposterior diameter changes of the rib cage and abdomen were measured during breathing maneuvers and utterance activities in an adult subject with flaccid paralysis of the rib cage, diaphragm, and abdomen. Data were charted to solve for lung volume, volumes of the rib cage and abdomen, chest wall configuration, and inferred neck muscle actions. Free breathing was accomplished through an alternate waxing and waning of neck muscle drive or through step-wise glossopharyngeal pumping. Connected speech was performed in breath groups begun by neck gestures that "cocked" the breathing apparatus and stored recoil energy in it for use during ensuing expirations. Some breath groups were also extended through intermittent glossopharyngeal pumping. Connected speech was characterized by frugal control of the air supply through compensatory adjustments in the larynx and upper airway. Compensations involved in the breathing maneuvers and utterance activities are described, and consideration is given to two understandings--the human potential for functional restoration and the clinical evaluation and management of individuals with neuromuscular impairment.
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Radiological analysis is the single most attractive objective method for assessing the long-term anatomical effects of rheumatoid arthritis. Measurement of x-ray changes has given us our most important clues on the effectiveness of disease-modifying drugs. Although no single system has been adopted by all investigators to quantify radiological changes, most investigators have used joint counts or scores which have many properties of an interval scale to measure erosions and, at times, joint space narrowing. More extensive use of radiological analysis in therapeutic trials, if based on a thorough understanding of the natural history of radiological progression in rheumatoid arthritis, should provide a more accurate appraisal of our ability to modify the course of the disease.
Gold therapy given to 73 patients with rheumatoid arthritis was associated with remission of synovitis for 3 months or longer in 27 patients and 50% or greater improvement in 20 patients. New joint deformities did not develop in patients who experienced remission, and progression of radiologically detectable erosive changes was prevented. Serum protein and serologic abnormalities were improved in all groups, but patients who had a good response experienced the greatest improvement. No single clinical or laboratory feature in the pretreatment assessment predicted response, but, as a group, the patients with the best response also ranked best for most prognostic indicators.
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Using a special gastroesophageal catheter, electromyographic measurements of the diaphragm (Edi) and transdiaphragmatic pressure (Pdi) were taken in the supine, standing, erect sitting, and leaning forward (sitting) positions in 8 normal subjects and 6 patients with severe chronic obstructive pulmonary disease (COPD) with marked hyperinflation and low fat diaphragms. Four patients had pronounced postural relief of their dyspnea from assuming the supine and/or leaning forward positions. All 8 normal subjects and 4 of the 6 patients with COPD showed substantial (2- to 5-fold) increases in delta Edi, the phasic inspiratory amplitude of Edi, on assuming the standing and erect sitting postures. In the normal subjects, delta Pdi, the phasic inspiratory increment in Pdi, was maintained in all 4 postures, whereas in all patients with COPD, it decreased significantly in the erect sitting and standing postures. In 2 of the 6 patients with COPD, the delta Edi did not increase in the erect postures. This suggested that in these patients a reflex, which normally compensates for reduced diaphragmatic efficiency because of shortened muscle fibers in the erect postures, was not operating. Although it is not clear what mechanism(s) might account for suppression of this compensatory reflex, such reflex suppression might be advantageous from the viewpoint of diaphragmatic muscle energetics. The diaphragm would be thus spared energetically wasteful attempts to accomplish a fatiguing mechanical task.
To define the regional ventilation of the human lung, subjects were monitored with a gamma camera, while breathing air labeled with radioactive 81mKr which is being continuously eluted from a generator. The information observed is displayed as a reiterated multiframe moving picture. This is accomplished by storing the information from multiple breaths, selecting acceptable cycles (determined by the duration of inspiration and expiration and the amplitude to extremes of the cycles), and normalizing the usable information and converting the summed data into sequential frames, which are repeatedly shown on a video screen from computer memory.
Polygraphic study in 18 men with the sleep apnoea syndrome showed central, upper airway obstructive, and mixed apnoeas. Fifty per cent of the total apnoea time was central, 33% was obstructive, and 17% was mixed. Apnoeic episodes were accompanied by oxygen desaturation, relative bradycardia and hypotonia of orofacial muscles innervated by ponto-medullary neurons. During regular breathing these muscles revealed tonic and phasic inspiratory EMG activities. The data suggest that the primary sleep apnoea syndrome results from a dysfunction of the central control of breathing.
It is established that during tidal breathing the rib cage expands more than the abdomen in the upright posture, whereas the reverse is usually true in the supine posture. To explore the reasons for this, we studied nine normal subjects in the supine, standing, and sitting postures, measuring thoracoabdominal movement with magnetometers and respiratory muscle activity via integrated electromyograms. In eight of the subjects, gastric and esophageal pressures and diaphragmatic electromyograms via esophageal electrodes were also measured. In the upright postures, there was generally more phasic and tonic activity in the scalene, sternocleidomastoid, and parasternal intercostal muscles. The diaphragm showed more phasic (but not more tonic) activity in the upright postures, and the abdominal oblique muscle showed more tonic (but not phasic) activity in the standing posture. Relative to the esophageal pressure change with inspiration, the inspiratory gastric pressure change was greater in the upright than in the supine posture. We conclude that the increased rib cage motion characteristic of the upright posture owes to a combination of increased activation of rib cage inspiratory muscles plus greater activation of the diaphragm that, together with a stiffened abdomen, acts to move the rib cage more effectively.
Four patients with severe chronic obstructive lung disease and recent respiratory failure are described in whom two distinct simultaneous respiratory rhythms were identified, one at 8 to 13 breaths per minute and the other at 39 to 65 per minute. Magnetometer measurements of thoracoabdominal motion together with simultaneous electromyograms of multiple inspiratory muscles suggested that both rhythms were the result of coordinated action of several inspiratory muscles. We suggest that this phenomenon, which we have called dirhythmic breathing, results from the conflicting influence upon respiratory centers and motoneurons of two or more stimuli, some favoring rapid shallow breaths and others slow deep breaths.
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Seventeen patients with sleep apnea were studied with reference to the frequency and duration of apneic episodies, the mechanism of the apnea and the extent to which oxygen saturation was depressed by the apnea. In all patients, esophageal pressure was recorded simultaneously with respiratory magnetometer records of rib cage and abdominal motion. Thermistor records from the nose and mouth indicated the presence of apnea. Nine patients had purely obstructive apnea and eight a mixture of central and obstructive apnea. In all instances the magnetometer records alone permitted distinction between obstructive and central apnea. Inspiratory efforts against an occluded airway produced a very different pattern of motion when compared to unobstructed breathing or to central apnea. We propose that magnetometer monitoring of thoracoabdominal motion indicates upper airway obstruction reliably and provides a noninvasive and thus more acceptable alternative to esophageal pressure recording for detecting upper airway obstructive apnea.
We report a case of respiratory failure caused by Strongyloides stercoralis in a patient with a renal transplant; the respiratory failure showed dramatic response to therapy with thiabendazole. The clinical aspects of infestation with S stercoralis in the immunocompromised host are discussed, and features are demonstrated which may have significant implications concerning primary treatment and prophylaxis.