Biomedical subjects

B L Roberts

Publications and source records attributed to B L Roberts.

At least 73 records · Page 4Linked to original sources

PubMed1991

Design, construction and function of a multicopy display vector using fusions to the major coat protein of bacteriophage M13.

Incorporation of numerous copies of a heterologous protein (bovine pancreatic trypsin inhibitor; BPTI) fused to the mature major coat protein (gene VIII product; VIII) of bacteriophage M13 has been demonstrated. Optimization of the promoter, signal peptide and host bacterial strain allowed for the construction of a working vector consisting of the M13 genome, into which was cloned a synthetic gene composed of a lac (or tac) promoter, and sequences encoding the bacterial alkaline phosphatase signal peptide, mature BPTI and the mature coat protein. Processing of the BPTI-VIII fusion protein and its incorporation into the bacteriophage were found to be maximal in a host bacterial strain containing a prlA/secY mutation. Functional protein is displayed on the surface of M13 phage, as judged by specific interactions with antiserum, anhydrotrypsin, and trypsin. Such display vectors can be used for epitope mapping, production of artificial vaccines and the screening of diverse libraries of proteins or peptides having affinity for a chosen ligand. The VIII display phage system has practical advantages over the III display phage system in that many more copies of the fusion protein can be displayed per phage particle and the presence of the VII fusion protein has little or no effect on the infectivity of the resulting bacteriophage.

Amino Acid Sequence↗

PubMed1991

Changes in size and number of spinal motoneurons in relation to growth of the musculature in the eel, Anguilla.

Estimates of the numbers of spinal motoneurones in relation to growth in the eel, Anguilla, were made by counting the axons contained within the ventral roots. Motoneuronal size was determined as the surface area of cell somata labelled retrogradely from applications of tracer (horseradish peroxidase, cobalt lysine) to the musculature or spinal nerves. The sizes and numbers of muscle fibres from red and white portions of the myotomal musculature were determined from frozen sections. Measurements of motoneurone size and number in relation to the size and number of the muscle fibres were obtained from the same body region for eels of body lengths ranging from 65 to 930 mm and for 3 different stages of the eel's life history (glass, yellow and silver eels). The mean sizes and the numbers of red and white muscle fibres, and motoneuron size, increase substantially in relation to body length; the numbers of axons in the ventral roots of fish of different body lengths, however, are very similar (approx. 130 per half segment). Silver eels are indistinguishable from yellow eels of a similar size with respect to the size and number of motoneurone somata and axons and to the number of muscle fibres. In silver eels red muscle fibres are similar in size to those of yellow eels, but the white fibres are larger.

Anguilla↗

PubMed1990

Dynamic characteristics of vestibular-driven compensatory fin movements of the dogfish.

Compensatory pectoral fin reflexes were studied in decerebrate dogfish subjected to sinusoidal oscillation (0.01-1.0 Hz). At 0.01 Hz the peak response of the depressor muscle was in phase with head position. At higher frequencies the phase advanced and at 1 Hz approached that of maximum angular velocity. Peak response amplitude was steady from 0.01 to 0.07 Hz but thereafter increased markedly. We suggest that the high frequency response depends upon vertical semicircular canal input.

Animals↗

PubMed1990

Nursing research in geriatric mental health.

As the population of older people in the world increases, concerns about the health and delivery of health care to these elderly people become increasingly more important. Geriatric mental health arose as a nursing specialty in response to this concern over the health of older adults. This paper focuses on a review of nursing literature relevant to the mental and cognitive health of older adults. Implications for current practice and future research are explored.

Aged↗

PubMed1990

Five year outcome of preterm sextuplets related to size at birth.

Preterm sextuplets were studied to examine whether growth retardation affects long term outcome. All were growing normally at 5 years. Intelligence quotients (IQ) ranged from 105-116 and motor impairment scores from 1.0-7.0. No neurological or behavioural abnormalities were found. The largest sextuplet has maintained her position for growth and IQ. No relation between test scores and birth weight or perinatal variables was found in the remaining siblings.

Birth Weight↗

PubMed1990

Effects of walking on reaction and movement times among elders.

The purpose of this study was to examine the effects of a 6-wk. walking program on reaction times and movement times among 52 elders. Twenty-seven elderly, whose mean age was 71.8 yr. comprised the experimental group, and 25 elderly whose mean age was 71.8 yr. comprised the comparison group. The former subjects walked for 30 min. three times a week for 6 wk. while the latter maintained their normal activity. No significant differences in simple or choice reaction times and the associated movement times were found. To clarify the relationship of health and current and past physical activity, correlations of these with both simple and choice reaction times and movement times were examined. Except for the number of miles walked in a week, none of the correlations were significant. These results may not support previous findings that reaction and movement times were shorter with life-long participation in aerobic activity. However, the present study examined persons who were sedentary and were not involved in a life-long participation in aerobic exercise. Implications of these findings are discussed.

Aged↗

PubMed1989

Immunocytochemical analysis of the dopamine system in the brain and spinal cord of the European eel, Anguilla anguilla.

The distribution of dopamine-containing perikarya and fibres in the central nervous system of the eel, Anguilla anguilla, was determined by using a specific dopamine antiserum. Telencephalic dopamine-immunoreactive somata are located in the external cell layer of the olfactory bulb and throughout the rostrocaudal extent of the subpallium; immunoreactive fibres are located primarily in the bulb and in ventral and lateral portions of the hemispheres. Diencephalic dopamine-immunoreactive neurons are associated with the ventricles in the preoptic area and hypothalamus and in the posterior tubercle. Many of the neurons in the hypothalamus are liquor-contacting. Very few immunoreactive neurons are located in the mesencephalon, and no dopamine-containing cells are found in regions that can be homologized with the ventral tegmental area and substantia nigra of amniotes. There is a rich innervation of the medial octavolateralis nucleus and certain layers of the torus semicircularis and of the tectum. Dopamine-containing neurons are located in the vagal lobe, by the vagal motor nucleus and in the area postrema, which provides a rich dopaminergic innervation of the brainstem motor column and of the reticular formation. Immunoreactive liquor-contacting neurons line the central canal and another type of labelled neuron lies dorsally in the spinal cord.

Anguilla↗

PubMed1989

Laterality and prematurity.

Lateral preferences were determined by postal questionnaire for 240 children, without major neurological impairment, who were born at less than 31 weeks' gestation to examine the association between neonatal brain injuries and later lateral preference. Left hand preference was reported in 64 (26.7%) children at a median age of 52 months (range: 24-104 months). Left foot preference was shown by 70 (29.2%) and left eye preference by 86 (35.8%). Significantly more preterm children were left handed compared with parents or siblings in whom expected frequencies of left handedness were found. All index children had serial neonatal cerebral ultrasound examinations, of which 95 were abnormal. Left preference occurred at similar frequencies in those with normal neonatal scans (26.9%), bilateral lesions (28.3%), left sided lesions (23.8%), and right lesions (23.8%). Lateral preference appears to be unaffected by the side or extent of neonatal brain injury in children without major impairments.

Brain↗

PubMed1989

Motor skills in extremely low birthweight children at the age of 6 years.

Fifty three children aged 6 years old who had weighed less than 1251 g at birth without cerebral palsy and receiving mainstream education, were entered into a controlled study of motor skills. The index and control children were matched by age, sex, and school. The index group were considered by their teachers to have similar academic performances to their index group were considered by their teachers to have similar academic performances to their controls, although two index cases were receiving remedial teaching. On the test of motor impairment extremely low birthweight children had significantly more motor difficulties than controls. In addition, the index group had more minor neurological signs, lower intelligence quotients, and more adverse behavioural traits. The higher motor impairment scores among index children were independent of differences in intelligence quotient between the two groups. There was no association between impairment score and the presence or degree of periventricular haemorrhage or periventricular leucomalacia on neonatal cerebral ultrasound. Children with Apgar scores at five minutes of less than 7 had significantly higher impairment scores compared with those whose scores were 7 or more. Three perinatal factors (Apgar score at five minutes, neonatal septicaemia, and abnormal movements) explained 32% of the variance in impairment score at the age of 6 years. In children who do not have cerebral palsy perinatal factors may still be important in the development of motor skills. The presence of subtle neuromotor impairments at 6 years of age has implications for schooling that need further evaluation.

Child↗

PubMed1988

Cognitive disturbance in hospitalized and institutionalized elders.

The purpose of this study was to examine the relationship between empirical findings and a theoretical model of cognitive disturbance among 94 hospitalized and 78 institutionalized elders. Path analysis was used to determine the magnitude of relationships between variables described in the model. Neural function was the only variable in both groups that was significantly associated with greater cognitive disturbance. In the hospitalized group, neural structural changes and physiologic alterations contributed indirectly to cognitive disturbance by their effects on neural function. Further, neural function indirectly affected cognitive disturbance through its effects on sensory deficits. In the institutionalized group, environmental deficits and neural functions were significantly related to greater cognitive disturbance. Except for the direct effects of neural function on activity limitations and physiologic alterations on mental health, all the relationships between the variables described by the model were significantly different between hospitalized and institutionalized elders. The results suggest that different interventions to reduce cognitive disturbances may be required for institutionalized and hospitalized elders.

Activities of Daily Living↗

PubMed1988

Sensory interaction with central 'generators' during respiration in the dogfish.

The activity in sensory and motor nerves of the gills was recorded from selected branches of the vagus nerve in decerebrate dogfish, Scyliorhinus canicula. Vagal motoneuronal activity was observed at the start of the rapid pharyngeal contraction and was followed by sensory nerve activity which preceded the slow expansion phase. Rhythmical vagal motoneuronal activity was still present after all movements had been prevented by curare paralysis although the frequency of the rhythm was higher than in the ventilating fish. Electrical stimulation of vagal sensory fibres had 3 effects on the ventilatory movements. (1) It evoked a reflex contraction of several gill muscles after a latency of about 11 ms. (2) It could reset the respiratory cycle because a stimulus given during expansion delayed the onset of the subsequent contraction. (3) The stimulus could entrain the rhythm if it was given continuously at a frequency close to that of ventilation. The vagal motor rhythm was disrupted by trigeminal nerve stimulation in the paralyzed fish but not if the motor rhythm was being entrained by vagal nerve stimulation. Vagal sensory activity may be important, therefore, in maintaining the stability of the generating circuits.

Animals↗

PubMed1988

Victims of Alzheimer's disease and the environment.

The environment plays an essential role in the functioning and care of older persons, particularly those with Alzheimer's disease. This article describes the characteristics of the environment that affect the functioning of persons with Alzheimer's disease and the interaction between the person and environment. Assessment and interventions based on environmental characteristics and person-environment interaction are identified.

Aged↗

PubMed1987

Immunohistochemical study of a dopaminergic system in the spinal cord of the ray, Raja radiata.

Using a specific antibody we have demonstrated the presence of an intrinsic dopamine (DA)-containing system in the spinal cord of a cartilaginous fish. The DA neurons are distributed throughout the spinal cord in the subependymal layer that surrounds the central canal. These cells extend a thick process into the canal and thinner neurites throughout the gray matter; they resemble the liquor-contacting neurons reported for a range of vertebrates.

Animals↗

PubMed1987

Distribution and morphological characteristics of efferent neurons innervating end organs in the ear and lateral line of the European eel.

Neurons that provide the efferent innervation to the labyrinthine and lateral line sense organs of the eel were located by applying horseradish peroxidase to branches of the appropriate cranial nerves. Retrogradely labeled neurons were found in a single median column, the octavolateralis efferent nucleus (OEN), located immediately rostral to and overlapping with the facial nucleus of the branchiomotor column. We estimate that on each side of the brain the efferent nucleus contains about 60-70 neurons, most of which supply the ear and the lateral line system of the head. Most neurons (approximately 90%) are ipsilateral to the targets they innervate. There is no crisp topographical order within the nucleus because neurons supplying different end organs intermingle. However, the head lateral line is supplied by rostrally located neurons, and the body system by more caudal neurons. There are no marked differences in cell form between neurons supplying different targets. Most are multipolar, relatively uniform in size, and have extensive dendrites. The dendrites of some cells extend to the contralateral side of the brain. Efferent axons are of small diameter (approximately 3 micron). Two neurons are sufficiently constant in size and location that they can be consistently recognized from fish to fish. Their axons branch to supply more than one target. Nearly all efferent neurons stain for acetylcholinesterase and some, bordering the midline, consistently stain weakly.

Acetylcholinesterase↗

PubMed1987

Distribution of afferent fibers in the brainstem from end organs in the ear and lateral line in the European eel.

Sensory nerve fibers from the lateral line system and labyrinth of Anguilla anguilla were labeled with horseradish peroxidase and traced to various targets in the ipsilateral brainstem. The three rami of the anterior lateral line nerve and the supratemporal ramus of the posterior lateral line nerve form overlapping terminal zones in the ventral portion of nucleus medialis. The posterior lateral line nerve on the body is represented exclusively in the dorsal half of the nucleus medialis. Eighth nerve fibers from the otolithic end organs in the inner ear send fibers into dorsal portions of three octavus nuclei: anterior, magnocellular, and descending, and saccular fibers lie most medial and utricular fibers most lateral. Fibers from vestibular organs, especially the semicircular canals and utricle, end densely in ventral portions of these nuclei and in the tangential nucleus. All labyrinthine sense organs send fibers into the region of a Mauthner-like neuron, and all except the saccule terminate in the reticular formation, tangential nucleus, and eminentia granularis of the cerebellum. Primary sensory input to the octavolateralis efferent nucleus comes only from the labyrinth, and fibers from the saccule alone penetrate the region of efferent neuronal somata. Fibers from labyrinthine end organs except the saccule project to the reticular formation where they may contact the dendrites of efferent somata. Fibers from the lateral line and the eighth nerve overlap most extensively at the rostral pole of the nucleus medialis and in the eminentia granularis of the cerebellum.

Afferent Pathways↗

PubMed1987

The effect of protein context on nuclear location signal function.

The effect of position and number and of another intracellular location signal on the activity of the nuclear location signal was investigated. A minimal signal was inserted into several sites within the polypeptide chain of pyruvate kinase. The results observed suggest that a nuclear location signal can function at a variety of positions within a protein but that in some locations its activity is masked. Multiple copies of a partially defective signal were integrated into pyruvate kinase. The data suggest that multiple signals can cooperate to enhance nuclear accumulation. A nuclear location signal failed to function when inserted into polyomavirus middle T but was active in an identical variant lacking the carboxy-terminal hydrophobic tail. We conclude that while a minimal nuclear location signal is sufficient for nuclear localization, its activity is crucially dependent on the protein context within which it is present.

Amino Acid Sequence↗

PubMed1987

Signal-dependent translocation of simian virus 40 large-T antigen into rat liver nuclei in a cell-free system.

An in vitro nuclear translocation system is described in which isolated rat liver nuclei were incubated in a defined buffered medium containing radiolabeled or fluorescently labeled exogenous proteins. The nuclei were rapidly recovered, extracted, and analyzed for the presence of associated radiolabeled or fluorescently labeled proteins. The isolated nuclei exhibited the same specificity for protein uptake as seen previously in vivo, accumulating simian virus 40 wild-type large-T antigen and p53 while excluding a cytoplasmic variant of large-T antigen (d10) and bovine serum albumin. The rapid nuclear accumulation of wild-type large-T antigen was shown to be selective and dependent upon the recognition of a wild-type nuclear location signal, ATP and temperature dependent, and unidirectional. Taken together, the data suggest that in our in vitro system the nuclear translocation of wild-type large-T antigen exhibits some of the characteristics of an active transport process.

Animals↗

PubMed1986

The relationship of saccular efferent neurons to the superior olive in the eel, Anguilla anguilla.

In the eel, horseradish peroxidase was applied to the saccular ramus of the eight nerve to label auditory efferent neurons and was injected into the torus semicircularis to identify the superior olive. Efferent somata cluster close to the lateral lemniscus. The superior olive is also associated with the lateral lemniscus and is situated just rostral to and contiguous with the efferent population. Efferent cells can be distinguished from superior olivary neurons because of their larger size and their positive acetylcholinesterase reaction. It appears that in these fishes, as in mammals, auditory efferent neurons are closely associated with the superior olive.

Animals↗