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Biomedical subjects

J Millar

Publications and source records attributed to J Millar.

At least 37 records · Page 2Linked to original sources
PubMed2000

Can spontaneous spinal epidural haematoma be managed safely without operation? A report of four cases.

The presentation, investigation, and management of four patients with spontaneous spinal epidural haematoma is presented. In each case the diagnosis was made by MRI. At the time of diagnosis spontaneous recovery had started in each patient and therefore they were all treated conservatively. In each case follow up MRI confirmed rapid reduction in the size of the haematoma and no underlying cause was demonstrated. The presentation, diagnosis, and rationale for treatment are discussed. Conservative treatment is safe in some cases of spinal epidural haematoma if early neurological recovery has started.

Adult↗
PubMed1998

Recovery of function processes in human amnesia: evidence from transient global amnesia.

There are few clues as to the processes that underlie recovery of function from human amnesia. Evidence is offered from the perspective of a study of recovery of function during an episode of transient global amnesia (TGA) that occurred as a complication of a cerebral angiographic procedure being carried out in a neurosciences centre, and where there was therefore a unique opportunity to examine acute changes in memory function. This allowed us to conduct the first quantitative study where shrinkage of anterograde and retrograde memory loss was plotted at four separate intervals throughout the acute recovery process, and also 24 hr later. Recovery of retrograde amnesia preceded recovery from anterograde amnesia. Resolution of a naming deficit more closely paralleled recovery from retrograde amnesia rather than anterograde amnesia. Within retrograde amnesia for public events, there was a temporal gradient of memory loss, with more recent events affected to a greater degree than earlier events. Within anterograde amnesia, picture recognition memory preceded recovery of story recall memory. On the basis of these findings, and related observations in the published literature, it is proposed that recovery from some types of human amnesia, such as that associated with TGA, follows a 'lateral-to-medial' rule--lateral inferotemporal areas that play a major role in retrograde amnesia recover first from hypometabolism related to the TGA attack, followed by 'interface' areas such as the rhinal and parahippocampal cortices that are considered to have a role in both anterograde and retrograde memory functioning, with the last areas to recover physiological integrity being discrete limbic-diencephalic structures such as the hippocampus.

Adult↗
PubMed1998

Differential release of dopamine by nitric oxide in subregions of rat caudate putamen slices.

Fast cyclic voltammetry was used to measure NO and dopamine (DA) simultaneously in rat caudate putamen (CPu) slices. Analysis of electrochemical signals obtained from mixtures of DA and NO showed that subtraction of either the DA or the NO component revealed the contribution of the other component. Application of such data manipulation to signals obtained in CPu slices indicated that DA and NO components contributed to electrochemical signals. Following electrical stimulation (>1 s), site-dependent NO-like signals were observed. Pressure ejection of NMDA yielded a biphasic electrochemical signal. The first phase (lasting 10-20 s) had electrochemical characteristics of DA and was observed only during the first application of NMDA. The second phase developed more slowly, was of longer duration (1-3 min), and had electrochemical characteristics of a mixture of DA and NO. Generation of the NO-like signal by NMDA was antagonised by L-N-monomethylarginine. Pressure ejection of NO into CPu slices caused dose- and site-dependent DA release. More DA was released in the dorsolateral than in the dorsomedial CPu. Pressure ejection of DA did not generate NO. It is concluded that electrically stimulated DA release is not mediated by prior release of NO.

Animals↗
PubMed1997

The zeta pulse: a new stimulus waveform for use in electrical stimulation of the nervous system.

A new waveform which can be used instead of pulses for general electrical stimulation of the nervous system is described. This new waveform has been called the 'Zeta' pulse. The potential advantages of the use of this waveform are discussed together with a brief review and discussion of the mechanisms of extracellular stimulation in nervous tissue. A circuit diagram for the generation of the Zeta waveform is given.

Action Potentials↗
PubMed1997

Very long-term amnesia in association with temporal lobe epilepsy: evidence for multiple-stage consolidation processes.

The temporal fractionation of long-term retention remains a relatively uncharted area in human memory research, and in particular there is little in the way of neuropsychological data that address this issue. We describe a patient with temporal lobe epilepsy who complained of amnesia for important events that had occurred in the previous 3-24 months, but who reported that her short-term and medium-term memory were normal. She displayed normal performance on traditional tests of short-term and long-term retention, performing at a very similar level to that of age- and sex-matched healthy control subjects on immediate and half-hour delayed recall measures. Forty days later, however, she showed a dense amnesia for recall of such information, whereas control subjects could readily recall much of the original stimuli. She also showed evidence of memory loss for news events that had occurred over the previous few years. MRI scanning and EEG brain mapping indicated left temporal lobe pathology, with a possible epileptogenic focus in the left anterior hippocampus. These data provide empirical evidence for the existence of a distinct very long-term consolidation process in human episodic memory and point to its neural correlates in the temporal lobe. Transfer of information into a permanent long-term memory store may entail multiple-stage consolidation processes rather than a single-stage, unitary consolidation process.

Amnesia↗
PubMed1997

Is day case surgery in urology associated with high admission rates?

The nature of the procedures and patients in urological day surgery may lead to high admission rates. A retrospective audit was performed over 8 years (1988 to 1996) to determine admission rates in a urological day surgical unit and examine reasons for and methods of decreasing admissions. The overall admission rate was 9.3%. Higher rates were associated with cystoscopic procedures, with 46% of admissions after bladder tumour cystosurveillance and a further 18% after urethroscopic surgery for urethral strictures. There was a surgical indication for admission in 72% of cases, with an anaesthetic indication in 17%. The study demonstrates that admission rates accompanying urological day surgery are higher than the 3% proposed by The Royal College of Surgeons of England. Achieving a rate of 3% may require restrictive patient selection that will deprive some patients the benefits associated with urological day surgical care.

Aged↗
PubMed1996

Long-term perceptual priming in transient global amnesia.

This paper addresses the question as to whether long-term perceptual priming can occur during transient global amnesia. A patient who displayed the classical features of transient global amnesia was assessed during the episode and again 7 days later. During the episode, she was administered a task that required the perceptual identification of fragmented pictures over a number of learning trials. Seven days later, after recovery from the episode, she was required to identify the same fragmented pictures together with a new set of pictures that she had never seen before. She was significantly better at identifying the old pictures than the new pictures, in spite of having amnesia for the period of the attack. Matched control subjects who had never seen either set of pictures before, were also tested and performed at a similar level on the old and the new pictures. Our findings extend the clinical domain of implicit memory phenomena and parallel similar observations in chronic amnesia (Cave & Squire, 1992). We provide the first demonstration of a residual capacity for long-term perceptual priming during an acute episode of apparent total loss of memory.

Amnesia↗
PubMed1996

Radiation treatment of superior sulcus lung carcinoma.

The survival of patients with superior sulcus lung carcinoma and the effects of treatment were reviewed. From a prospective database of 4123 consecutive new patients with lung carcinoma, 131 (3.2%) cases of superior sulcus lung carcinoma were identified. Seventy-four patients were planned to receive radiation with palliative intent, 53 radical radiotherapy and one was observed only. The remaining three patients, with small-cell carcinoma, were treated with chemotherapy with or without radiotherapy. Of the 53 radically treated patients, nine were treated with pre-operative radiation prior to intended radical resection. Analysis was carried out on the effect on survival of performance status, nodal involvement, weight loss, vertebral body or rib involvement, treatment intent and radical combined modality treatment compared with radical radiation alone. The estimated median survival for the whole group was 7.6 months; for those treated radically it was 18.3 months, while for the palliatively treated patients it was 3.7 months. Radically treated patients with no initial nodal involvement had an estimated median survival of 22 months, while radically treated patients with nodal involvement had an estimated median survival of 8.4 months (P = 0.003). There were no statistically significant differences in survival between radically treated patients grouped according to initial weight loss, performance status, or vertebral body and rib involvement. Patients treated with pre-operative radiation did not survive significantly longer than patients treated with radiation alone, although the numbers are small.

Adult↗
PubMed1996

Day surgery and community health services work load: a descriptive study.

This prospective descriptive study of primary health care workload in the five days after day surgery is based on a questionnaire to patients who received day surgery in a specialist unit in Oxford. Half of all patients received health care, the mean consultation time was 16 minutes, and half the consultations were within two days of surgery.

Ambulatory Surgical Procedures↗
PubMed1995

The putative dopamine D3 agonist, 7-OH-DPAT, reduces dopamine release in the nucleus accumbens and electrical self-stimulation to the ventral tegmentum.

The present experiments were designed to test further the idea that 7-OH-DPAT (7-hydroxy-N,N-di-n-propyl-2-aminotetralin), a putative dopamine (DA) D3 agonist, has effects at DA autoreceptors to reduce intracranial DA levels and to reduce behaviours that are DA-dependent. Rats were trained to respond on a self-stimulation protocol for electrical stimulation to the ventral tegmental area (VTA). Each press of a lever delivered a 0.5 s train of square wave, 1.5 ms duration, 100 Hz, 90-120 mA stimulation. Systemic administration of 7-OH-DPAT at 0.01-0.3 mg/kg i.p., quickly dose-dependently reduced responding. Electrical stimulation using similar parameters to those that supported self-stimulation were then applied to the VTA of anaesthetized rats. Fast cyclic voltammetry (FCV) revealed that this stimulation released DA in the nucleus accumbens (NAC). 7-OH-DPAT i.p. (0.1-3.0 mg/kg) quickly and potently reduced the size of the DA-generated voltammetric signal. This effect of 0.3 mg/kg 7-OH-DPAT was not blocked by sulpiride (60 mg/kg, i.p.) a D2-specific antagonist that may preferentially block D2 autoreceptors. These data are discussed with reference to the possibility that 7-OH-DPAT reduces the release of dopamine in the NAC, at D3, but not at D2, autoreceptors and that this in turn may reduce the rewarding effect of VTA stimulation.

Animals↗
PubMed1995

The nitric oxide/ascorbate cycle: how neurones may control their own oxygen supply.

The brain requires an extremely precise means of controlling oxygen delivery to neurones. Too much, and the cells risk free-radical-mediated damage: too little, and the neurones die from hypoxic-excitotoxic mechanisms. Although nitric oxide (NO) is a powerful vasodilator in cerebral blood vessels, synthesis of NO from arginine requires oxygen and so is unsuitable as the mediator of hypoxia-induced cerebral vasodilation. This paper describes a model in which ascorbate, released from neurones during activity, generates NO from the reduction of nitrite ions in the extracellular space. This mechanism could subtly and accurately match the oxygen transport to the local metabolic demands of the nerve cells. The model predicts that the consequences of low ascorbate in the brain would be progressive damage from inaccurate oxygen delivery.

Animals↗