Search PubMed⌕ Search

Biomedical subjects

B Bishop

Publications and source records attributed to B Bishop.

At least 55 records · Page 3Linked to original sources
PubMed1982

Neural plasticity. Part 4. Lesion-induced reorganization of the CNS: recovery phenomena.

Most patients treated by physical therapists have suffered some neurological trauma resulting from disease or injury. The traditional teaching used to be that damage of central neurons is irreversible. Within the last decade, however, it has been necessary to cast aside this traditional view because of accumulating evidence that the brain is endowed with remarkable plasticity. This paper reviews experimental evidence revealing morphological and functional changes occurring in the CNS in response to neural lesions. Morphological responses to injury include collateral and terminal sprouting, retrieval of vacated synapses, alterations in the ultrastructure of surviving synapses, and denervation supersensitivity. Functional and adaptive changes induced by injury include the unmasking of ineffective synapses, shifts in receptive fields, and reorganization or altered effectiveness of surviving neural networks. These recovery phenomena attest to the brain's dynamic properties. These new insights contradict our conventional view of the absence of growth and reorganizational capabilities in CNS neurons. These newly identified "recovery phenomena" are destined to have a significant impact on physical therapy in the future.

Afferent Pathways↗
PubMed1982

Neural plasticity: Part 1. Plasticity in the developing nervous system: prenatal maturation.

The origin and development of the nervous system is a gradual process of cell division, migration, and specialization. The establishment of neural circuits requires cell-to-cell recognition. Despite an unceasing search, the mechanisms accounting for this cell-to-cell recognition remain unknown. In contrast, the stages in prenatal development from conception to birth and the sequence of events in the formation of the nervous system are known in considerable detail. The major purpose of Part 1 is to review the ontogeny of the spinal nervous system, with emphasis on the continuous remodeling phenomena that occur as a result of changes in neuronal activity or in the biochemical milieu. The underlying rationale for focusing on the details of prenatal maturation is to identify and analyze cell-to-cell interactions and to define their critical periods. This type of information is expected to provide explanations for previously unexplained developmental phenomena, to improve ability to diagnose and prognosticate in newborns with congenital anomalies of the nervous system, and to provide therapists with insights for improving treatment techniques for neonates with neurological deficits.

Female↗
PubMed1982

Neural plasticity: Part 2. Postnatal maturation and function-induced plasticity.

At birth, the central nervous system has completed most of its early stages of cell division, migration, and specialization. Much of the neural circuitry has been laid down. Neuroblasts are continuing to divide only in limited brain regions. Hence, at birth, most mammals have a nearly full complement of neurons. Nonetheless, the functional capabilities of the central nervous system of the newborn have little resemblance to those of the adult. Postnatal maturation must proceed in the proper sequence and at the proper rate if central nervous system deficits in the adult are to be avoided. Many of the prenatal maturational phenomena described in the previous paper continue well into the postnatal period. The purpose of this paper is to describe some postnatal maturational mechanisms and to show, by selected examples, the important role that function and experience play in central nervous system development.

Animals↗
PubMed1982

Neural plasticity: Part 3. Responses to lesions in the peripheral nervous system.

This paper describes some of the remarkable recuperative responses that neurons of the peripheral nervous system have to injury of their axons. The initial response is a sealing of the cut ends of the axons, followed by orderly degenerative and phagocytic events in the segments lying distal and proximal to the lesion. The chromatolytic changes occurring in the cell body are adaptive responses involving the morphological, physiological, and biochemical properties of the neuron. The cell loses dendrites and synapses, its electrophysiological properties are altered, and its biochemistry is altered to prepare the neuron for synthesizing proteins needed for formation of growth cones and regeneration of the axon. During this period, the denervated muscle undergoes dramatic atrophic changes that not only modify the electrical nd chemical properties of its membrane but also reduce the diameter and weight of its fibers. This denervation atrophy of muscle is reversible if reinnervation occurs before muscle material has been replaced by connective tissue. Responses to injury of sensory axons depend on the site of the lesion. Cutting a dorsal root causes Wallerian degeneration of the primary afferents' central processes. Collateral sprouts from neighboring uncut root fibers are thought to take over the vacant synapses on the second-order neurons in the dorsal horn. Cutting a sensory axon peripherally eliminates the receptive field of the primary afferent initially, but in time, collaterals from neighboring skin afferents provide the second-order neurons with a new receptive field. Synaptic reclamation and receptive field reorganization are but two dramatic examples of neuronal plasticity that lead to "rewired" neural circuitry.

Atrophy↗
PubMed1982

Human breathing patterns on mouthpiece or face mask during air, CO2, or low O2.

Steady-state breathing patterns on mouthpiece and noseclip (MP) and face mask (MASK) during air and chemostimulated breathing were obtained from pneumotachometer flow. On air, all 10 subjects decreased frequency (f) and increased tidal volume (VT) on MP relative to that on MASK without changing ventilation (VE), mean inspiratory flow (VT/TI), or mean expiratory flow (VT/TE). On elevated CO2 and low O2, MP exaggerated the increase in VE, f, and VT/TE due to profoundly shortened TE. On elevated CO2, MASK exaggerated VT increase with little change in f. Increased VE and VT/TI were thus due to increased VT. During low O2 on MASK, both VT and f increased. During isocapnia, shortened TE accounted for increased f; during hypocapnia, increased f was related primarily to shortened TI. Thus the choice of a mouthpiece or face mask differentially alters breathing pattern on air and all components of ventilatory responses to chemostimuli. In addition, breathing apparatus effects are not a simple consequence of a shift from oronasal to oral breathing, since a noseclip under the mask did not change breathing pattern from that on mask alone.

Adult↗
PubMed1982

Enzyme-linked immunosorbent assay for measurement of anti-Moraxella bovis antibodies.

Antibodies of the immunoglobulin (Ig) G and IgA classes specific for Moraxella bovis in serum or lacrimal secretions of cattle were detected with an enzyme-linked immunosorbent assay, using soluble extracts of M bovis or whole organisms. The amount of detectable antibodies was influenced by the type of antigenic preparation used in the enzyme-linked immunosorbent assay. The test indicated that 2 subcutaneous inoculations of M bovis cells induce significantly (P less than 0.0001) increased anti-M bovis serum antibodies. The infection of calves with M bovis induced specific IgG antibodies in serum and predominantly IgA antibodies in lacrimal secretions.

Animals↗
PubMed1981

The effect of voluntary activity on the masseteric silent period duration.

This study examined both TMJ and normal groups for any changes in the masseteric silent period with variation of the subjects' occlusal force. An analog meter was used to give each subject feedback on how hard the teeth were clenched together. Five silent periods were elicited at each of the four levels of occlusal force from 40% to 100% of maximum force. Results showed a small decrease in silent period duration for both groups when occlusal force was increased.

Dental Occlusion, Centric↗
PubMed1981

Respiratory sinus arrhythmia in humans: how breathing pattern modulates heart rate.

The relationship of respiratory sinus arrhythmia amplitude (RSA) to tidal volume and breathing frequency was quantified during voluntarily controlled tidal volume and breathing frequency and spontaneous quiet breathing. Seventeen seated subjects breathed via mouthpiece and nose-clip, maintaining constant tidal volumes at each of several breathing frequencies. Inspiratory breath hold was zero frequency. Log RSA was plotted vs. log frequency for each tidal volume. The large stable RSA for frequencies less than 6 cycles/min was called low-frequency intercept (LFI, 20 +/- 5 beats/min). Low-frequency intercept was inversely proportional to a subject's age only to 35 yr. At higher breathing frequencies above a characteristic corner frequency (fC, 7.2 +/- 1.5 cycles/min) RSA decreased with constant slope (roll-off; 21 +/- 3.4 dB/decade). The RSA-volume relationship was linear permitting normalization of RSA-frequency curves for tidal volume to yield one curve. Spontaneous breathing data points fell on this curve. Voluntarily coupling of heart rate to breathing frequency in integer ratios reduced breath-by-breath variability of RSA without changing mean RSA. In conclusion, low-frequency intercept, corner frequency, and roll-off characterize an individual's RSA-frequency relationship during both voluntarily controlled and spontaneous breathing.

Adult↗
PubMed1981

Single motor unit activity in the diaphragm of cat during pressure breathing.

In this study we analyzed the breath-by-breath activity of single motor units in the diaphragm slip of allobarbital-anesthetized cats during quiet breathing and during continuous positive- and negative-pressure breathing. Our objective was to determine whether single motor units, on the basis of their activities, can be separated into discrete subpopulations or whether they fall on a continuum analogous to that of motor units of hindlimb muscles. The firing profiles of each unit were characterized for each pressure level by the onset and peak firing frequencies, onset latency, duration of firing, number of impulses per breath, and minimal frequency, when appropriate. Units with shorter onset latencies had higher peak frequencies, longer firing durations, and increased firing frequencies than did units with longer onset latencies. These comparative relationships persisted even though the activity of every motor unit was altered during pressure breathing. During positive-pressure breathing onset latencies were lengthened, and durations of firing were shortened with little change in onset or peak frequencies. Late units might be silenced. During negative-pressure breathing onset latencies were shortened, and durations of firing were lengthened, sufficiently in some cases to fill the expiratory pause. In addition, previously inactive units were recruited late in inspiration for short, relatively high frequency bursts during inspiration. The results support the concept that the phrenic motoneuron pool is comprised of three discrete subpopulations.

Airway Resistance↗
PubMed1981

Volume, flow, and timing of each breath during negative airway pressure in humans.

We have analyzed the effects of 4-6 min of 5, 10 and 15 cmH2O continuous negative airway pressure breathing (NPB) on steady-state end-expiratory lung volume (delta VR) and breathing pattern. Fourteen healthy adults, seated in a full body box, breathed via a mouthpiece on a bag-in-box. Pressure in the body box was elevated to the desired pressure level. Inspiratory (TI) and expiratory (TE) durations, tidal volume (VT), minute ventilation (VI), mean inspiratory flow (VT/TI), and mean expiratory flow (VT/TE) were calculated from pneumotachometer recordings. The effects of NPB are decreases in delta VR, VT, and VT/TI and increases in VT/TE. The responses to NPB are an increase in breathing frequency, due to a shortened TE, and an increase in inspiratory activity. The decrease in delta VR and the increase in VT/TE are limited by an active retardation of expiratory flow. End-tidal CO2 and VI were not altered significantly during NPB, suggesting no alveolar hyperventilation. Thus multiple components of the human response to NPB are not all engaged at the same levels of NPB. The changes in the timing of respiratory events occur at -5 cmH2O, whereas VT compensation is not seen until -15 cmH2O.

Adult↗
PubMed1980

Pain: its physiology and rationale for management. Part I. Neuroanatomical substrate of pain.

Pain, one of man's most worrisome afflictions, is also one of neurobiology's most challenging problems. Even its definition is beset with controversy. The origin and current resolution of this controversy are presented in this paper, but the major purpose of Part I is to review the anatomical substrate of the peripheral and central nervous systems involved in pain. Structural and functional characteristics of pain receptors and their afferent fibers are described, with emphasis upon current hypotheses regarding putative neural transmitters and possible mechanisms for signal transduction. Hitherto unrecognized details of the cytoarchitecture, anatomical organization, and circuitry of the dorsal horns are reviewed. The paper concludes with a consideration of the major components of the ascending and descending systems of subserving pain.

Central Nervous System↗
PubMed1980

Pain: its physiology and rationale for management. Part II. Analgesic systems of the CNS.

The analgesic effects of morphine and other opiates have long been recognized, but the mechanisms underlying these effects have only recently been uncovered. First, opiate receptors were discovered and their distribution throughout the central nervous system mapped. Then endogenous morphine-like copmounds, called endorphins and enkephalins, were identified. One of the most promising aspects of understanding the physiology and pharmacology of these endogenous opiates is conquering control over pain.

Afferent Pathways↗
PubMed1980

Pain: its physiology and rationale for management. Part III. Consequences of current concepts of pain mechanisms related to pain management.

Part III of this review describes the impact that acupuncture, our drug culture, and the gate-control theory have had on our progress in elucidating pain mechanisms and in treating pain syndromes. Whether an analgesis is produced by morphine, acupuncture, or electrical stimulation of an appropriate brain region, the analgesia can be blocked by naloxone, a morphine antagonist. This observation, among others, suggests that similar effector mechanisms involving endogenous opiates serve all three types of analgesia. Although the gate-control theory must continually be revised to accord with new information, it has been a major impetus for stimulating fruitful research.

Acupuncture Therapy↗
PubMed1978

Volume, flow, and timing of each breath during positive-pressure breathing in man.

This study is a breath-by-breath analysis of the effects of 5, 10, and 15 cmH2O positive-pressure breathing (PPB) on man's steady-state breathing pattern. Inspiratory (TI), expiratory (TE), and cycle (TT) durations, tidal volumes (VT), minute ventilation (VE), mean inspiratory flow rate (VT/TI), and mean expiratory flow rate (VT/TE) were determined from pneumotachograph and Wedge spirometer recordings before and during steady states on PPB. End-tidal CO2 was continuously recorded. Seventeen adults, seated in a full body-box, breathed quietly for 8 min through a mouthpiece on a bag-in-box. Pressure in the body-box was lowered to the desired level prior to 4 min of stress. On all pressure levels, end-expiratory volume, VT, VE, VT/TI, and VT/TE increased; end-tidal CO2, TE, and TT decreased with no consistent change in TI. Calculated alveolar ventilations indicated that the increases in VE were true hyperventilations. Each individual increased VE by using a unique combination of VT, TI, and TE. End-expiratory volume increased less and expiratory flow increased more than would occur passively. Hence, it is concluded that active reflexes account for the resistance of the systems to the passive distention, the facilitation of expiratory flow, and the shortening of TE.

Adult↗
PubMed1978

Noninvasive localization pheochromocytomas.

Because of the propensity for extra-adrenal sites, preopertative localization of pheochromocytomas remains an important operative determinant. Although arteriography has been widely considered to be the procedure of choice for preoperative localization, in this series of 13 patients, falsely negative arteriograms were seen on two occasions while four patients experienced significant morbidity from attempts at angiographic localization. Emphasis is placed upon noninvasive techniques as the initial approach toward localization. The value of bolus infusion nephrotomography is re-emphasized and localization of a pheochromocytoma by ultrasound and computerized axial tomography is described.

Adolescent↗