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Biomedical subjects

A M Smith

Publications and source records attributed to A M Smith.

At least 343 records · Page 19Linked to original sources
PubMed1985

Labelling of cerebellar mossy fiber afferents with intra-axonal horseradish peroxidase.

Several unidentified units recorded in the intermediate zone of lobules IV and V of the cerebellar cortex responded to superficial radial nerve stimulation with a distinctive short train of 5 to 11 low amplitude spikes (less than 5 mV) at a frequency of 800 to 1200 Hz. Responses of this type have in the past been attributed to mossy fiber afferents. Following the electrophysiological characterization horseradish peroxidase was successfully injected by iontophoresis into four axon terminals. The labelled axons presented the typical structure of mossy fibers with terminal rosettes and corresponded to the morphology of these axons described in Golgi material.

Afferent Pathways↗
PubMed1985

Experimental pneumococcal otitis media: longitudinal studies in the gerbil model.

In order to ascertain that the Mongolian gerbil, Meriones unguiculatus, is an acceptable model for studying the development of chronic from acute otitis media, we used previously published methods for experimental otitis media in a longitudinal study of the acute disease and sequellae. The gerbil was found to be susceptible to as few as 30 viable Streptococcus pneumoniae type 3 cells, indicating that only a few viable pathogens are able to cause the disease. Untreated experimental infections with S. pneumoniae type 23 resulted in a mild, self-limiting disease with little permanent sequellae, while S. pneumoniae type 3 produced severe disease characterized by an acute phase of from 2 to 3 weeks, followed by the development of new bone formation and a vascularized granulation tissue which persisted throughout the 13-week study. Viable pneumococci could be recovered from the middle ears for only two weeks. We conclude that the gerbil is a useful model for otitis media.

Animals↗
PubMed1985

Folate intake and blood concentrations of term infants.

Folate nutrition of 67 full-term infants was studied longitudinally from birth to 1 year. Infants were grouped according to type of milk consumed during early infancy: group I (n = 14) received human milk; group II (n = 31), a standard cow-milk infant formula; and group III (n = 22), the same formula with added iron (12.3 mg/L). Solid foods were introduced after 3 months. Folate status, as indicated by serum and red blood cell folate concentrations, and folate intake were measured periodically. Blood folate concentrations of all groups were higher than or similar to adult control values. No differences in indices of folate status were observed between formula-fed groups at any time frame. At 6 weeks and 3 months formula-fed infants had folate intakes and blood concentrations significantly greater than human milk-fed infants. With the introduction of solid foods, decreases in blood folate concentrations paralleled decreases in milk folate intake within each group. Serum folate concentrations correlated with both total folate intake and milk folate intake, whereas RBC folate concentrations correlated with only milk folate intake. The results indicate that milk, regardless of type (human milk, formula, and cow milk), is an important dietary source of folate during the first year of life and that both human milk and proprietary formula feeding during early infancy provide more than sufficient folate to maintain blood folate concentrations well above acceptable limits.

Animals↗
PubMed1985

A decade of drug information experience in Northern Ireland.

A decade of service by the Regional Drug Information Service in Northern Ireland, and the need for this service to solve drug problems is described. The development of a combined Drug Information Service and Poison Information Service at the Royal Victoria Hospital, Belfast, is outlined.

Drug Information Services↗
PubMed1985

Transbronchial needle aspiration in clinical practice.

Transbronchial needle aspiration has recently been adapted for use with the flexible bronchoscope. We studied 108 patients, who had a total of 110 aspirations performed, and diagnosed thoracic cancer in 70 cases. Transbronchial needle aspiration revealed malignant disease in 32 (46%) of these 70 patients. In 12 (17%) patients with cancer this technique provided the sole cytological or histological confirmation of the diagnosis. It gave a positive result in an additional 20 (29%) cases in which the diagnosis was also proved by conventional procedures, and it provided important staging information in these patients. In 20% of patients with cancer transbronchial needle aspiration precluded the need for further diagnostic surgery. There were no complications in this series. This is a safe, useful, and economical technique that can be used in diagnosing and staging patients with carcinoma of the lung.

Biopsy, Needle↗
PubMed1985

Cerebellar nuclear cell activity during antagonist cocontraction and reciprocal inhibition of forearm muscles.

Monkeys were trained to exert a maintained isometric pinch with the thumb and forefinger. This task reliably elicited a simultaneous cocontraction of the forearm muscles. The same monkeys were also taught to insert the open hand into a manipulandum, flex and extend the wrist 35 and 15 degrees, respectively, and maintain an isometric wrist position against a mechanical stop for 1 s. This second task comprised two conditions: a dynamic or movement phase and a static or isometric phase. Movement always involved a wrist displacement of 50 degrees. Although some forearm muscles demonstrated bidirectional activity during the wrist displacement phase, all the wrist and finger muscles were alternatively active in isometric flexion or extension. Of the neurons in the dentate and interposed nuclei that consistently changed discharge during repeated isometric prehension, over 90% (61/67) of the neurons increased activity during this cocontraction of forearm muscles. About 70% (47/67) of these same nuclear cells discharged with a reciprocal pattern of firing during alternating wrist flexion-extension movements. Forty-six neurons had sustained and reciprocal discharge during the maintained isometric wrist postures. No differences were seen between the activity patterns of dentate and interposed cells with respect to either the prehension task or the reciprocal wrist-movement task. The discharge frequency of some dentate and interpositus neurons could be correlated with prehensile force as well as velocity of wrist movement and torque developed by wrist muscles. Correlation coefficients were calculated between nuclear cell discharge and the amplitude of the surface EMGs of the flexors and extensors of the wrist and fingers during the wrist-movement task. Sixteen nuclear cells showed low-order, but reliably positive, correlations with one of the two forearm muscle groups (mean r = 0.33). In contrast, a sample of seven Purkinje cells recorded during the same task demonstrated low-order correlations that were negative in sign (mean r = -0.30) between discharge frequency and one of the two forearm EMGs.

Animals↗
PubMed1984

Development of a self-administered questionnaire to measure maternal adjustment and maternal attitudes during pregnancy and after delivery.

Having a baby entails very great changes in maternal intrapsychic and interpersonal adjustment, and childbearing is associated with an increased risk of psychiatric disorder. It may be possible, as pregnancy progresses, to find clues to such disturbances among the changes that occur in maternal attitudes and self-perceptions, This report describes the development and validation of a 60-item, self-administered questionnaire which aims to measure a mother's perceptions of her body, of somatic symptoms, the marital relationship, attitudes to sex and attitudes to the pregnancy and the baby. A pilot study of 99 women in late pregnancy was followed by repeated measures taken from 119 first-time mothers who were subjects in a longitudinal survey of mental health in a routine obstetric service setting. The questionnaire was acceptable to the mothers, it was reliable (test-retest and split-half) and comparisons with independently gathered interview data showed that it had criterion-related validity. The questionnaire is appended to this report (Appendix I).

Attitude↗
PubMed1984

Cerebellar cortical activity during antagonist cocontraction and reciprocal inhibition of forearm muscles.

Monkeys were trained to perform a maintained isometric grip of the thumb and forefinger that elicited a simultaneous cocontraction of the antagonist muscles of the forearm. The same monkeys were also trained to flex and extend the wrist against a stop with the fingers extended and to maintain an isometric wrist position for 1.0-1.5 s. During wrist movement, some of the synergist forearm muscles contracted during both flexion and extension. However, during the maintained isometric wrist position, the prime mover and synergist muscles were reciprocally active or silent. In the culmen-simplex region of the cerebellar cortex bordering on the primary fissure, 62% of the Purkinje cells that were identified by the climbing fiber discharge and that changed firing frequency decreased activity during maintained prehension. Almost all of these same Purkinje cells were reciprocally active during isometric wrist flexion and extension, although three neurons had similar discharge patterns during movements in both directions. In contrast, 79% of the unidentified neurons recorded from the same region of the cerebellar cortex increased discharge frequency during prehension. In general, most of these same neurons had reciprocal patterns of discharge during wrist movement even though a few cells were active during the dynamic phase in both directions. Together, the Purkinje cells and the unidentified neurons with bidirectional response patterns were thought to be related to muscles active during both flexion and extension wrist movements. No cells were found that increased discharge with the static isometric wrist torque exerted in both directions. The discharge frequency of some Purkinje and some unidentified neurons could be shown to be related to prehensile force as well as wrist movement velocity and isometric wrist torque. These data suggest that the discharge of about two-thirds of the Purkinje cells related to forearm muscles located along the borders of the primary fissure may depend on whether antagonist muscles are activated reciprocally or coactively. As a consequence, these cells may play a role in the selection or alternation between either of these two modes of muscular contraction. The increased discharge of the remaining one-third of the Purkinje cells excited during antagonist coactivation may provide inhibition of nuclear cells to stabilize the posture at joints other than the wrist and fingers or, alternatively, they may act to reduce nuclear cell discharge in proportion to the intensity of cutaneous stimulation.

Animals↗
PubMed1984

Influence of multi-holed shakers on salting on food.

In a study of 2241 Australian adults consuming main meals at a cafeteria, single-and multi-holed (5, 9, 13) salt shakers were weighed before and after use. For all hole numbers, salt use increased linearly with an increase in hole area to a maximum value of 1.1-1.2 g which was the same irrespective of hole number. For a given hole area multi-holed shakers decreased salt use compared with single-holed shakers suggesting that multi-holed shakers are easier for consumers to control. However the greatest restriction in salt use (0.37 g per meal) is obtained by use of a single-holed shaker of 3 mm2 hole area.

Australia↗
PubMed1984

Contributions of foods to sodium in the Australian food supply.

The sodium contributions of various foods in the Australian supply have been calculated by applying recent local food composition data to food availability data and to typical notional Australian diets. Sodium available for consumption from the food supply was 3.00 g per capita per day. Of foods which are salted during processing, the three heaviest contributors of sodium were bread (23 per cent of total available sodium), processed meat and fish (14 per cent), and margarine (8 per cent). Other important contributors were breakfast cereals, biscuits, cheese, butter, potato crisps, dried soups and cakes (including pastries, pies and puddings). Foods identified by health authorities as 'highly salted' and thus prime targets for reduced consumption, provided 33 per cent of total available sodium, less than the 50 per cent contributed by other foods salted during processing. Take-away foods per se did not contribute more sodium than processed foods generally.

Adolescent↗
PubMed1984

Salting of take-away foods at point of purchase.

Sodium and potassium levels were determined in ten types of fried take-away foods and sandwiches purchased from retail outlets with and without the addition of salt by the food handler. In virtually all foods the major source of sodium was that added during manufacture of the food ingredients rather than that added by the food preparer.

Food↗
PubMed1983

Ethylene enhances reactivity of superoxide with peroxidase to form the oxy-ferrous complex.

Ethylene and its analogues acetylene, carbon monoxide, and propylene inhibited the rate of oxidation of indole-3-acetic acid by peroxidase. Annulment of this effect by addition of superoxide dismutase showed that inhibition occurred only in the presence of the superoxide anion radical (O2-.). Kinetic and spectral data established that ethylene and its analogues enhanced markedly the rate of reaction of O2-. with peroxidase. This reaction resulted in the formation of compound III, an oxy-ferrous complex of peroxidase. In the presence of indole-3-acetic acid, the interaction between ethylene, peroxidase, and O2-. activated the reduced peroxidase in equilibrium compound III shuttle. O2-. is a major product of this shuttle, and compound III constitutes the dominant steady-state form of peroxidase. These interactions may help to explain the mechanism of action of ethylene as a plant growth regulator.

Acetylene↗