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Biomedical subjects

J B North

Publications and source records attributed to J B North.

At least 19 recordsLinked to original sources
PubMed1999

Tottering mouse motor dysfunction is abolished on the Purkinje cell degeneration (pcd) mutant background.

Tottering (tg) mice inherit a recessive mutation of the calcium channel alpha 1A subunit gene, which encodes the pore-forming protein of P/Q-type voltage-sensitive calcium channels and is predominantly expressed in cerebellar granule and Purkinje neurons. The phenotypic consequences of the tottering mutation include ataxia, polyspike discharges, and an intermittent motor dysfunction best described as paroxysmal dystonia. These dystonic episodes induce c-fos mRNA expression in the cerebellar circuitry, including cerebellar granule and Purkinje neurons, deep cerebellar nuclei, and the postsynaptic targets of the deep nuclei. Cellular abnormalities associated with the mutation include hyperarborization of brainstem nucleus locus ceruleus axons and abnormal expression of L-type calcium channels in cerebellar Purkinje cells. Here, the role of these two distinct neural pathways in the expression of tottering mouse intermittent dystonia was assessed. Lesion of locus ceruleus axons with the neurotoxin N-(2-chloroethyl)-N-ethyl-2-bromobenzyl-amine (DSP-4) did not affect the frequency of tottering mouse dystonic episodes. In contrast, removal of cerebellar Purkinje cells with the Purkinje cell degeneration (pcd) mutation by generation of tg/tg; pcd/pcd double mutant mice completely eliminated tottering mouse dystonia. Further, the c-fos expression pattern of tg/tg; pcd/pcd double mutants following restraint was indistinguishable from that of wild-type mice, suggesting that the pcd lesion eliminated an essential link in this abnormal neural network. These data suggest that the cerebellar cortex, where the mutant gene is abundantly expressed, contributes to the expression of tottering mouse dystonic episodes.

Animals↗
PubMed1994

False aneurysm following intracranial surgery.

A false aneurysm of the pericallosal artery formed following resection of a colloid cyst. The aneurysm presumably resulted from arterial damage during surgery and its enlargement may have been facilitated by the surgical defect in the corpus callosum. A spherical hyperdense lesion on postoperative CT may indicate a false aneurysm.

Adult↗
PubMed1993

Tumours of the brain and presence of antibodies to Toxoplasma gondii.

The possible association between prior infection with the protozoan Toxoplasma gondii and development of brain tumours was investigated as part of two Australian population-based case-control studies of adult brain tumours. One study, based in Adelaide, South Australia, collected blood from 73 subjects with glioma, 53 subjects with meningioma and 348 controls. The other study, based in Melbourne, Victoria, collected blood from 44 subjects with glioma and 67 controls. All tumours had been verified histologically. IgG antibodies to T. gondii were measured using Enzyme Linked Immunosorbent Assay (ELISA) techniques. In both the centre-specific and combined analyses, there was no difference between subjects with glioma and controls in the prevalence of antibody test-positivity (35% test-positive in glioma versus 33% in controls, age-, sex- and centre-adjusted odds ratio (OR) = 1.00, 95% confidence interval (CI): 0.64-1.56). In the Adelaide study, there was a statistically significant increased risk of meningioma associated with antibody test-positivity (47% test-positive in meningioma versus 31% in controls, P = 0.02, adjusted OR = 2.09, 95% CI: 1.14-3.83). Our results do not support the hypothesis that antibody positivity to T. gondii is a risk factor for glioma, but suggest that it might be associated with meningioma.

Adult↗
PubMed1993

Extradural haematoma: trends in outcome over 35 years.

We have reviewed 35 years experience of extradural haemorrhage (EDH) in a large neurosurgical unit, based in two university hospitals, one dealing exclusively with children and the other a general hospital. A steady reduction in the mortality rate from 29 to 8.5% occurred during that period. A trend towards earlier diagnosis is noted and an increasing proportion of rural patients has been evident throughout the study period. During the time-period studied there were many significant developments: the establishment of a modern neurosurgical unit, the evolution of an intensive care unit, the availability of CT head scanning and the formal organization of rapid retrieval to service country areas. However, no single feature could be identified as the major contributor to falling mortality results. Clinical awareness and early diagnosis are the keys to successful management of EDH.

Adolescent↗
PubMed1993

Primary (granulomatous) angiitis of the central nervous system with multiple aneurysms of spinal arteries. Case report.

A 55-year-old woman with primary (granulomatous) angiitis of the central nervous system in association with non-Hodgkin's lymphoma (mucosa-associated lymphoid tissue type) presented with an acute spinal subdural hemorrhage secondary to rupture of one of several fusiform inflammatory aneurysms of the spinal cord radicular arteries. The literature on hemorrhagic complications, aneurysms, and spinal cord involvement in granulomatous angiitis is reviewed. Recognition of granulomatous angiitis is important, as the condition may be responsive to immunosuppressive therapy.

Aneurysm↗
PubMed1992

The relative effects of hypoxic hypoxia and carbon monoxide on brain function in rabbits.

New Zealand white rabbits were exposed to control conditions (n = 11), or to either a progressive hypoxic hypoxia produced by dilution of oxygen (O2) with nitrogen (n = 10) or a 1% carbon monoxide (CO) admixture for 15 min (n = 11). Both exposures caused a significant increase in cerebral blood flow (CBF) of up to 300% such that O2 delivery to the brain was unchanged. In the hypoxia group, a cortical somatosensory evoked response (CSER) was unaffected until the arterial O2 tension was below 20 mmHg. At this time, the rabbits became hypotensive, O2 delivery to the brain decreased dramatically and the CSER could not be elicited. In contrast, despite the maintenance of O2 delivery to the brain during and after the CO exposure, the CSER voltages were halved during the exposure and only recovered to about 80% of baseline subsequently. We conclude that the primary toxicity of CO to the brain in rabbits is not due to a reduction in O2 delivery.

Animals↗
PubMed1991

Iatrogenic spinal subdural haematoma.

Spinal subdural haematoma is a rare condition, usually seen in association with lumbar puncture or a bleeding disorder. It carries a high morbidity and mortality, and successful treatment requires prompt surgical intervention. We present a case of mixed spinal subarachnoid and subdural haemorrhage complicating failed spinal anaesthesia combined with anti-coagulation in an elderly woman, together with a review of the literature.

Aged↗
PubMed1991

Primary central nervous system lymphoma. A report of 9 cases and review of the literature.

Primary central nervous system (CNS) lymphoma appears to be on the increase. This increase is real rather than due to changes in nosology, physician awareness or increase in high-risk groups. Diagnostic guidelines appear to be well defined and widely accepted. We report 9 cases of primary CNS lymphoma seen at our institution over a 5-year period. The clinical presentation was variable, but consisted mostly of headache, motor dysfunction, and memory and behavioural disturbance. Surgery is of value for diagnosis. In general, surgical decompression is not recommended. Glucocorticoids and radiotherapy appear effective in the short term. The role of chemotherapy is uncertain.

Adult↗
PubMed1991

Arachnoid cyst presenting as an extradural haematoma.

A case of extradural haematoma as the presenting feature of an arachnoid cyst is described. Haemorrhagic complications of arachnoid cysts are well known, but extradural haematoma is rare. A possible pathogenetic mechanism is proposed and the treatment of asymptomatic arachnoid cysts is discussed.

Adolescent↗
PubMed1990

Extradural haemorrhage in infancy and childhood. A review of 35 years' experience in South Australia.

One hundred and two paediatric cases of extradural haemorrhage (EDH) were treated in Adelaide, South Australia, during the period 1954-1988; 10 were infants (0-2 years) and 92 were children (2-14 years). There were 9 deaths (mortality 8.8%). Long-term disabilities severe enough to interfere with school and/or employment were seen in 8 (7.8%) survivors. This relatively low number of adverse outcomes is partly an expression of a low incidence (5.9%) of associated intradural haematomas and few high-velocity impacts due to vehicular accidents. There is reason to believe that the results of treatment have improved in the decade 1977-1988. We attribute this in part to early diagnosis by computed tomography (CT), but a contributory factor may be earlier referrals from country centres to a paediatric trauma centre and rapid transfer, by air or road, by medical retrieval teams.

Adolescent↗
PubMed1990

Synapses, axonal and dendritic patterns of GABA-immunoreactive neurons in human cerebral cortex.

Gamma-aminobutyric acid (GABA) containing neurons were characterized in human association cortex by a combination of Golgi impregnation and immunohistochemistry. Neurons were Golgi impregnated, gold toned, drawn and then classified on the basis of their dendritic and axonal arborization in layers I-VI. An antiserum to GABA was used to determine which of the impregnated neurons were immunopositive. Twenty-four GABA-positive cells were Golgi impregnated: 7 were bitufted with their dendrites predominantly radially oriented, and 17 were multipolar stellate cells. Three of the multipolar cells with large somata in the deep layers showed dendritic patterns similar to previously described basket cells. Nine of the multipolar stellate cells in layers III-VI showed characteristics of 'neurogliaform' neurons (Ramón y Cajal, 1899). The somata and the dendritic field of these cells were spherical, with diameters of about 10-15 microns and 200 microns, respectively. Their dendrites were smooth and slightly beaded. The axon collaterals were densely distributed in and around the dendritic field, in a spherical area with a diameter of at least 300 microns. The thin axon collaterals had only occasional 'en passant' swellings. Contacts between the axons of neurogliaform cells and the distal dendrites of Golgi-impregnated pyramidal cells were observed. Electron microscopic immunocytochemistry revealed that GABA immunopositive nerve terminals formed symmetric synaptic contacts with somata, with GABA immunonegative and immunopositive dendritic shafts and with dendritic spines. The results show that GABAergic neurons are heterogeneous with respect to their dendritic and axonal patterns. In addition to the chandelier and basket cells, which have been shown in animal studies to contain GABA, other cell types, most prominently the neurogliaform cells, terminating on the distal parts of neurons, also contain GABA and may have a inhibitory function. Many of the GABAergic terminals make synapses on dendritic spines and shafts in the human cerebral cortex.

Adolescent↗
PubMed1989

Diffuse axonal injury in head trauma.

Diffuse axonal injury (DAI) as defined by detailed microscopic examination was found in 34 of 80 consecutive cases of head trauma surviving for a sufficient length of time to be clinically assessed by the Royal Adelaide Hospital Neurosurgery Unit. The findings indicate that there is a spectrum of axonal injury and that one third of cases of DAI recovered sufficiently to talk between the initial head injury producing coma and subsequent death. The macroscopic "marker" lesions in the corpus callosum and dorsolateral quadrants of the brainstem were present in only 15/34 of the cases and represented the most severe end of the spectrum of DAI.

Axons↗
PubMed1988

Arachnoid cysts: a critical review of 41 cases.

Forty one cases of arachnoid cyst are reviewed that were treated at the Adelaide Children's Hospital and the Royal Adelaide Hospital. The pathogenesis of the cysts is discussed as well as the method of treatment. Certain aspects of this condition are still unsolved.

Adolescent↗
PubMed1988

Extradural haemorrhage: strategies for management in remote places.

A study of 109 cases of extradural haemorrhage (EDH) treated in South Australia over a period of 7 years showed that 35 cases (32.1 per cent) presented in country areas at considerable distances from a neurosurgical service: the mortality in these country cases was 22.9 per cent, comparing unfavourably with a mortality of 12.2 per cent in metropolitan cases. The country series contained a disproportionately large number of cases with multiple intracranial haemorrhages, which are known to have a poorer outcome; when these cases were excluded, the rural mortality (12.5 per cent) was only a little over the metropolitan mortality (9.7 per cent). These data suggest that it is possible to manage extradural haemorrhages successfully even in places remote from a neurosurgical centre, if communications and air transport are used effectively. However, it was found that emergency operations carried out in country hospitals were sometimes inadequate or done too late. Medical retrieval teams based on city hospitals were sent out on 15 occasions, either to assist a general surgeon to complete an emergency operation, or to provide intensive care during transfer to a neurosurgical unit. Osmotherapy (mannitol and/or frusemide) has been useful in gaining time for transfer; the choice between immediate operation and transfer may be difficult, and decisions should take transfer time, clinical state and rate of deterioration into account.

Acute Disease↗
PubMed1986

Acute subdural haematomas: aetiology, pathology and outcome.

The aetiology, mechanisms of haemorrhage and results of treatment of a series of 63 consecutive cases of acute subdural haematoma are presented. Forty-six cases were due to trauma (46% mortality) and 17 cases were non-traumatic (41% mortality). Only 15 patients overall (24%) made a good recovery. The various mechanisms of venous and arterial bleeding leading to subdural haematoma are reviewed and the importance of brain swelling as a determinant of fatal outcome is stressed.

Adolescent↗
PubMed1986

Preventable causes of death and disability from neurotrauma.

Preventable causes of death and disability have been studied retrospectively in a series of 1161 cases of neurotrauma occurring in New South Wales in 1977-78, and prospectively in 153 cases of neurotrauma occurring in country districts in South Australia in 1981-82. In the first study, it was found that at least 80 deaths could be attributed to preventable causes; chiefly, transfer to an inappropriate hospital and/or delay in instituting treatment. Apparent failures in initial management of shock and airway obstruction were evident in this study and also in the South Australian study, which identified major deficiencies in cardiorespiratory management in 7% of cases transferred from country areas. These studies confirm that there is a need for better training, at all levels, in the management of neurotrauma. They also provide powerful arguments for the concept of an integrated regional trauma service.

Australia↗
PubMed1986

Epidemiology and clinical outcomes of neurotrauma in New South Wales.

This study of 1161 neurotrauma patients in New South Wales hospitals was designed to examine the role of preventable causes of death and disability in cases of spinal injury, extradural, subdural and multiple intracranial haematomas in order to make recommendations for improvements in accident, emergency, ambulance and hospital services. Methods have been developed for standardizing diagnosis in different classes of hospital for the assessment of severity in terms of the patient's age, sex, physical signs, head and spine injuries and other injuries. Estimates have been made of the number of preventable deaths by a case control study of each category of neurotrauma under study.

Adolescent↗