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Biomedical subjects

A D Milner

Publications and source records attributed to A D Milner.

At least 199 records · Page 11Linked to original sources
PubMed1985

A deficit in ambient visual guidance following superior colliculus lesions in rats.

Rats were tested for their ability to locate a hidden platform in the Morris swimming pool in which extrapool cues are required to guide locomotion. At the end of each trial, the rats were either removed immediately or allowed to remain on the platform for 60 s. Bilateral lesions of the superior colliculus (SC), as in a previous experiment (Milner & Lines, 1983), were found to produce a severe deficit. Permitting the rats to stay on the platform did not significantly affect performance in either rats with SC lesions or sham-operated controls. The results indicated that the reduced orienting behavior on the platform observed in the rats with lesions in the previous experiment was not the cause of their navigational impairment. It is concluded that the impairment following SC lesions comes about during the swimming itself and therefore that it may be attributed to a disturbance of, or a failure to utilize, ambient vision.

Animals↗
PubMed1985

Manipulation of ventilator settings to prevent active expiration against positive pressure inflation.

Recent publications have suggested that in infants receiving artificial ventilatory support a particular pattern of interaction between spontaneous breaths and ventilator inflations (active expiration against each ventilator inflation) may be important in the production of pneumothoraces. We have looked at patterns of interaction from 47 preterm infants studied on 51 occasions. We found that active expiration against the ventilator occurred on a total of 16 occasions. This pattern was prevented on 14 occasions by altering the ventilator settings. In two other babies, the pattern persisted but neither baby developed a pneumothorax.

Carbon Dioxide↗
PubMed1985

Continuing respiratory problems three and a half years after acute viral bronchiolitis.

We reviewed the clinical progress of 81 children as part of a prospective study three and a half years after admission to hospital with acute viral bronchiolitis in infancy. Fifty six (69%) reported episodes of lower respiratory symptoms continuing over the preceding year, 25 (31%) had symptoms lasting for longer than two weeks on two or more occasions, 14 (17%) had symptoms for more than 100 days, and six (7%) required readmission to hospital with acute respiratory illness. Two years previously, these percentages had been 82%, 36%, 33%, and 13% respectively. Forty six (57%) children were said to be improving or to have become asymptomatic, but eight (10%) were deteriorating. There was no difference in the personal or family history of atopy, nor in the rate of skin test positivity between those with and without continuing symptoms, suggesting that atopy does not play an important role in the persistence of symptoms. Less than half the symptomatic children had received bronchodilator treatment during the preceding 12 months.

Acute Disease↗
PubMed1985

Inspiratory time and tidal volume during intermittent positive pressure ventilation.

We measured the tidal volume achieved during intermittent positive pressure ventilation using various inspiratory times with a minimum of 0.2 seconds. Results indicate that tidal volume shows no reduction with inspiratory times down to 0.4 seconds. An inspiratory time of 0.3 seconds, however, is likely to reduce tidal volume by 8%, and at 0.2 seconds a 22% fall may be anticipated.

Humans↗
PubMed1985

Pressure volume characteristics of the lungs in sudden infant death syndrome.

Data on the pressure volume characteristics of left lungs obtained from 23 babies dying from sudden infant death syndrome were compared with results from 18 length-matched babies dying from established but primarily non-pulmonary causes. Volume distension at 30 cm of water and deflation flow volume characteristics were very similar in the two groups. These findings do not suggest that babies dying from sudden infant death syndrome have abnormally stiff lungs.

Body Height↗
PubMed1985

Effects of positive end expiratory pressure during ventilation of the preterm infant.

Twenty two babies receiving artificial ventilator support were studied on 29 occasions to determine the effects of low levels of positive end expiratory pressure. Mean positive end expiratory pressure during these studies was 2.6 cm H2O. Changes in tidal volume, minute volume, compliance, and transcutaneous gas trends produced by the use of positive end expiratory pressure were investigated. Positive end expiratory pressure consistently caused a rise in transcutaneous oxygen tension. Changes in transcutaneous carbon dioxide tension after the introduction of positive end expiratory pressure were less consistent and not of the same magnitude as the observed reduction in minute ventilation. Compliance values fell with the use of positive end expiratory pressure.

Apnea↗
PubMed1985

Visual evoked potentials to lateralised stimuli in two cases of callosal agenesis.

Visual evoked potentials (VEPs) to lateralised light flashes were recorded from two acallosal patients. In one patient, these recordings were made while he performed a choice-reaction time task, and in the other patient the VEPs were obtained during a simple reaction time task. In both cases the patient's VEPs from electrode sites contralateral to the visual field of stimulus delivery resembled those of controls. Their VEPs from ipsilateral sites were aberrant, however, in that while control subjects showed a smaller and slightly delayed ipsilateral N160 component, this was not discernible in the patients' data. It is concluded that the ipsilateral N160 relies for its generation on the transcallosal transfer of information processed initially by the contralateral hemisphere.

Adult↗
PubMed1984

Efficacy of facemask resuscitation at birth.

The efficacy of facemask resuscitation was assessed by measuring the expiratory tidal volume during the first three inflations in nine babies with birth asphyxia and comparing the results with those obtained in a further nine babies resuscitated after endotracheal intubation. The facemask system was relatively inefficient, with tidal exchange less than one third of that seen after intubation and rarely sufficient to produce adequate alveolar ventilation. Successful resuscitation depended on stimulating the baby to make his own respiratory efforts.

Asphyxia Neonatorum↗
PubMed1984

The effect of stimulus intensity on visual evoked potential estimates of interhemispheric transmission time.

Visual evoked potentials (VEPs) to bright or dim lateralised light flashes were recorded from homologous occipital and central sites. In a GO/NOGO reaction time task (Experiment 1) the latency of the N160 component of the VEP was found to be shorter from the contralateral hemisphere by approximately 16 ms at occipital sites, but only 3 ms centrally. In addition, there was a trend for the occipital contralateral latency advantage to increase with decreasing stimulus brightness. In Experiment 2 a wider intensity range and a simple visual reaction time task were employed. Contralateral N160 latency advantages were again found to be larger occipitally (approx 13 ms) than centrally (3 ms). Furthermore the occipital contralateral latency advantage was significantly increased at the lower stimulus intensity, while that from central sites remained constant. These data suggest that two types of interhemispheric relay can be distinguished-a sensory one recorded occipitally and a non-sensory one recorded from central sites.

Corpus Callosum↗
PubMed1984

Visual orientation and detection following lesions of the superior colliculus in rats.

Rats with bilateral lesions of the superior colliculus (SC) or with sham operations were trained on a modified version of the running task of Goodale and Murison (1975). The rats were required to shuttle between two large boxes, one of which required a choice between 5 doors, the other having only 1 door. A flashing distractor light at the side of a box was subsequently presented on once-daily test trials. For half the rats of each group these tests were given at 1 month and for the others at 3 months post-operatively. In agreement with previous studies, the SC-lesioned rats showed an abolition of orienting reactions to the distractor. (This was so in both boxes, i.e. a lower attentional load in the running task failed to alleviate the SC lesion-induced deficit.) However, only in the early-tested rats did the lesion cause a loss of freezing response to the distractor. Since in the late-tested group the rats froze but did not orient, it is suggested that the orienting loss at least in their case cannot be attributed to a partial visual field defect.

Animals↗
PubMed1984

Visual evoked potentials to lateralized visual stimuli and the measurement of interhemispheric transmission time.

Visual evoked potentials (VEPs) to lateralized light flashes were recorded from the parietal midline, and from homologous occipital and central sites, in a GO/ NOGO reaction time task. The N160 component of the VEP was found to be larger over the hemisphere contralateral to the visual field of stimulus exposure at all pairs of lateral electrodes. At the occipital sites only, N160 latency was also shorter from the contralateral hemisphere, by an average of approximately 14 msec. This was not so centrally, where a non-significant value of approximately 4 msec was obtained. These data are considered to be consistent with Milner and Lines' hypothesis that callosal transmission occurs at different rates in different functional regions of the corpus callosum.

Cerebral Cortex↗
PubMed1984

Nebulised ipratropium bromide and sodium cromoglycate in the first two years of life.

In a double blind crossover trial, we compared sodium cromoglycate, ipratropium bromide, and water in 23 asthmatic children less than 2 years old (mean age 11.8 months). Each child received nebulised solutions containing 20 mg of sodium cromoglycate, 250 micrograms of ipratropium bromide, or 2 ml water three times a day for three two month periods. Daily symptom scores did not show significant differences between the treatments but parental preferences indicated that both sodium cromoglycate and ipratropium bromide were superior to placebo. Sodium cromoglycate was prophylactic and was more likely to help the older patients. Ipratropium bromide produced an immediate clinical benefit and the response was not age dependent. We were unable to pick responders from non-responders on the basis of lung function tests performed on a routine outpatient basis. Both ipratropium bromide and sodium cromoglycate help some but not all asthmatic children aged less than 2 years.

Aerosols↗
PubMed1984

High and conventional rates of positive pressure ventilation.

We compared high frequency positive pressure ventilation with conventional rate ventilation in 23 preterm infants with the idiopathic respiratory distress syndrome. Nine infants (10 studies) were making spontaneous respiratory efforts during conventional ventilation that abated at 100 breaths per minute. Six of these showed an increase in TcPo2 of at least 10% at the higher rate (mean 18.5%). Two babies showed no change during high frequency positive pressure ventilation, and in one baby (the largest) the TcPo2 fell. Eight infants were apnoeic at both ventilator rates: five suffered a fall in TcPo2 of at least 10% at 100 breaths per minute (mean 19%) and three were unchanged. A further six infants (seven studies) would not tolerate a reduction in rate from 100 breaths per minute without an increase in FIO2. Failure to tolerate a conventional ventilator rate in these circumstances seemed related to the onset or a noticeable increase in spontaneous respiratory efforts.

Carbon Dioxide↗
PubMed1984

Effect of exogenous surfactant on total respiratory system compliance.

We measured total respiratory system compliance (Crs) before and after instilling 25 mg artificial surfactant in 1 ml saline down the endotracheal tube of preterm babies requiring resuscitation at birth, and compared results with data from 6 similar babies receiving saline only. Surfactant did not produce a significant improvement in Crs.

Clinical Trials as Topic↗
PubMed1984

Neurones responsive to faces in the temporal cortex: studies of functional organization, sensitivity to identity and relation to perception.

We have investigated the distribution of cells responsive to faces within the macaque temporal cortex and their sensitivity to different face attributes. We found a functional organization of cells responsive to the sight of different views of the head. Cells of a similar type were grouped together both vertically down through the cortex, and horizontally in patches extending 0.5-2.0 mm across the surface of the cortex. A substantial proportion of cells responsive to faces were found to be sensitive to biologically important characteristics such as identity or expression. Cells were found to be highly selective for particular individuals that were familiar to the monkey with selectivity persisting across a great variety of viewing conditions such as changing face expression, orientation, colour, distance and size. Data suggested that sensitivity to identity arises at the level of specific views of the individual (e.g. full face). Information about different views may then be pooled to allow recognition independent of view. Visual transformations that make it difficult for humans to perceive faces (e.g., contrast reversal, isoluminant colour, coarsely quantized images, rotation or inversion) reduced the magnitude or increased the latency of cells' responses to faces. In this way, cell responses were related to perception and not simply to visual qualities of the image.

Adolescent↗
PubMed1983

Serology testing as a means of encouraging rubella immunisation.

One thousand three hundred and sixty-one women were tested for rubella antibody titres both under public and occupational conditions. Two hundred and seventy-one of the thirteen hundred and sixty-one women (20%) had low immunity. Follow-up methods resulted in immunisation of 55% of these women (149 of 271). Reasons for non-acceptance are explored. While a higher acceptance rate would be desirable, mass testing for antibody levels has been demonstrated as a method of encouraging those with low immunity to be immunised.

Adolescent↗