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Biomedical subjects

D G Thomas

Publications and source records attributed to D G Thomas.

At least 217 records · Page 12Linked to original sources
PubMed1984

Serum MBP immunoreactivity and immunoglobulin level as markers of tumour type.

Forty three patients, admitted to the department of Neurological Surgery for management of central nervous system tumours, were studied pre-operatively for serum myelin basic protein immunoreactivity as a marker of central nervous system lesion and for circulating immunoglobulins and complement (C3) levels. Myelin basic protein concentration did not appear to correlate with tumour type or grade. Serum immunoglobulin levels were found to be within the normal range but the mean IgM level was significantly higher in the glioma group when compared with meningiomas.

Adult↗
PubMed1984

Pre- and post-operative changes in serum immunoglobulin level in neurosurgical patients.

46 patients treated by operative neurosurgery for spontaneous subarachnoid haemorrhage, intracranial tumour and spinal diseases were studied. Levels of circulating immunoglobulin and complement were measured pre-operatively and serially in the first 10 post-operative days. Prior to operation immunoglobulin levels in all categories of patients were distributed normally. However, immediately post-operatively IgG and IgM fell sharply. Conversely IgA rose in a marked manner and C3 levels showed a gradual increase. Later, antibody levels tended to return to normal.

Complement C3↗
PubMed1984

Positron emission tomography in the study of cerebral tumours.

Positron emission tomography (PET) uses the shortlived positron-emitting radioisotopes of elements such as oxygen, nitrogen, and carbon as tracers both to image and to measure, non-invasively, normal regional tissue physiology and pathophysiology in man. This technique has been used to study the pathophysiology of brain tumours at the time they present and after therapeutic intervention.

Astrocytoma↗
PubMed1984

Developmental changes in the amount of glial fibrillary acidic protein in three regions of the rat brain.

Glial fibrillary acidic (GFA) protein, extractable in 50 mM phosphate buffer, pH 8, was measured in the olfactory bulbs, forebrain and cerebellum of the rat during development using a double antibody radioimmunoassay. Each brain region showed a different pattern of development for GFA protein. At birth GFA protein per mg protein was highest in olfactory bulbs followed by forebrain and cerebellum, and these amounted to 15, 10 and 8% of the adult values, respectively. The relative increase in GFA protein was more marked during the first 2 postnatal weeks than in the following 7 weeks after birth. When values were expressed per brain region, the developmental increase in the amount of GFA protein from birth to adulthood was about 100-fold in olfactory bulbs, 85-fold in forebrain and 485-fold in cerebellum. The patterns of developmental increases in GFA protein and in glutamine synthetase activity, another protein enriched in astrocytes, were similar in the forebrain and olfactory bulbs, but differed markedly in the cerebellum. The major increase in content of the GFA protein during development was found to correspond with the maturation of astrocytes rather than with their proliferation; however, a small but significant amount of GFA protein acquired at an early age may be related to increase in astroglial cell numbers in the cerebellum.

Age Factors↗
PubMed1984

Quantitative measurement of blood-brain barrier permeability using rubidium-82 and positron emission tomography.

In normal brain, the blood-brain barrier (BBB) is highly impermeable to K+ cations, their transport being controlled by ATPases situated in the endothelial cell membranes. 82Rb+ is a positron-emitting analogue of K+ with a half-life of 75 s. Using a steady-state model and positron emission tomography, quantitative extraction data for 82Rb+ transport across the BBB have been obtained both in normal human subjects and in a variety of conditions of cerebral pathology. A mean cerebral Rb extraction of 2.1% was found for normal subjects, corresponding to a mean value of 1.1 x 10(-6) cm s-1 for 82Rb+ cation permeability across the BBB. No increase in cerebral Rb extraction was observed for patients with diffusely raised intracranial pressure secondary to obstructive hydrocephalus and benign intracranial hypertension, or for patients with multiple sclerosis or cerebral systemic lupus erythematosus. Cerebral tumours that were enhanced on computed tomography scanning showed a significant increase in local Rb uptake. No correlation between tumour size, or grade of glioma, and tumour Rb extraction was found. Nonenhancing tumours showed no increase in local Rb extraction, and regions of perifocal tumour oedema also had Rb extraction values in the normal range. It is concluded that increased Rb extraction occurs only where tight junction integrity in the BBB breaks down locally, that is, in the microcirculation of enhancing tumours but not in that of perifocal regions of tumour oedema or nonenhancing tumours.

Adult↗
PubMed1984

The use of urodynamic studies to assess the effect of pharmacological agents with particular references to alpha-adrenergic blockade.

A method of studying the effect of drugs on the lower urinary tract is described, using cord-injured patients with detrusor hyperreflexia. In this study 19 patients received intravenous phentolamine. This alpha-adrenergic blockade produced a significant reduction in the maximum voiding detrusor pressure, voided volumes and peak flow rates with no reduction of outflow tract obstruction.

Humans↗
PubMed1984

The upper renal tracts in adolescents and young adults with myelomeningocele.

The state of the upper urinary tracts has been assessed in 181 adolescents and young adults with myelomeningocele. At the age of 16 years, abnormalities were present in 75 patients (41 per cent); the risk of these complications was related to the extent of the neurological deficit and the presence of a urinary diversion. During follow-up into early adult life, fresh or further deterioration of the upper renal tracts occurred in 48 patients (27 per cent); the pattern of this deterioration was influenced by whether or not previous urinary diversion had been performed.

Adolescent↗
PubMed1984

Effect of dexamethasone on glutamine synthetase and glial fibrillary acidic protein in normal and transformed astrocytes.

The effect of dexamethasone on astrocyte differentiation was investigated in vitro, using cultures of normal and transformed astrocytes. The astrocyte-enriched proteins glutamine synthetase (GS) and glial fibrillary acidic (GFA) protein were used as markers of astrocyte differentiation. Ethanol, the vehicle for dexamethasone, decreases GS activity and increases GFA protein concentration in cultures of the established cell line U251MG and in the majority of cultures of transformed astrocytes derived from varying grades of astrocytoma. Ethanol has no effect on primary cultures of astrocytes derived from immature rat brain. Dexamethasone increases GS activity and decreases GFA protein concentration in cultures of U251MG and a grade IV astrocytoma-derived culture, in comparison with ethanol control. Our results show differential effects of two factors on cell-specific proteins in normal and transformed astrocytes.

Animals↗
PubMed1984

CT-guided stereotactic neurosurgery: experience in 24 cases with a new stereotactic system.

Twenty-four cases have been operated upon using a prototype Brown-Roberts-Wells, CT-guided stereotactic neurosurgical system. This device has proved to be practical and flexible in clinical use. No CT scanner modifications were required, a fact which simplified its use in more than one hospital. Multiple targets can be biopsied with ease and relative safety. Drainage and other therapeutic procedures can be carried out with minimal hazard. Future applications of this system may include its use with NMR and PET images.

Biopsy↗
PubMed1984

Myelin basic protein immunoreactivity in serum of neurosurgical patients.

Patients admitted to the neurosurgical wards for the management of nervous system tumours, subarachnoid and intracerebral haemorrhage, head injury, spinal and peripheral nerve lesions, and other miscellaneous neurosurgical conditions, were studied by assay of serum immunoreactivity for myelin basic protein. Of 171 patients, 70% proved to have elevated myelin basic protein activity. In cerebral cases the extent of brain damage assessed by clinical methods appeared to correlate with the appearance of elevated serum myelin basic protein. In spinal and peripheral nerve cases no similar elevation of myelin basic protein was observed.

Adolescent↗
PubMed1984

Dorsal root entry zone lesions (Nashold's procedure) in brachial plexus avulsion.

Dorsal root entry zone coagulation (DREZ) lesions for pain were made in 41 patients at the National Hospitals during 1980 through 1983. In 34 patients the operation was an attempt to relieve pain due to avulsion of the brachial plexus. Of these patients, 95% were male and 91% had received their injury in road traffic accidents. The follow-up period is 4 to 44 months. Pain relief was good in 62%, fair in 24%, and poor in 14%. Postoperative motor or sensory changes occurred in 50% of the patients, but these were significant in only 12%. In later patients in this series, pre-, peri-, and postoperative monitoring of somatosensory evoked potentials was used. Evoked potential monitoring indicated subclinical posterior column damage ipsilateral to avulsion before DREZ lesion making in about 50% of the cases; in some cases, postoperative changes were detected.

Adult↗
PubMed1984

Intramedullary spinal cord tumours presenting as scoliosis.

Intramedullary spinal cord tumours may present as scoliosis without neurological signs. Those treating spinal deformities should be alert to this possible aetiology. The clinical features of 12 such cases are discussed with reference to early diagnosis and treatment. Patients with a painful scoliosis should be investigated with myelography as well as bone scintigraphy. Many intrinsic spinal cord tumours are now amenable to surgical removal. The prognosis for neurological recovery is poor once a severe deficit becomes established. The importance of early diagnosis and joint orthopaedic and neurosurgical management is emphasised.

Adolescent↗
PubMed1984

Pre- and postoperative changes in serum myelin basic protein immunoreactivity in neurosurgical patients.

In 44 patients undergoing neurosurgical procedures for intracranial tumors, subarachnoid hemorrhage, or spinal and peripheral nerve lesions, serum myelin basic protein (MBP) immunoreactivity was measured preoperatively and serially in the first 10 postoperative days. The double-antibody radioimmunoassay method was used, with a detection limit of 2.5 ng/ml in serum. Clinical evaluation was carried out at admission and on successive days during the period of neurosurgical management; outcome was assessed later. In the early postoperative phase, there was a fall in MBP immunoreactivity in all groups of patients. In the groups with intracranial tumor and subarachnoid hemorrhage, there was a subsequent rise in MBP immunoreactivity before the end of the 10-day period, which was not found in the group with spinal and peripheral nerve lesions.

Adenoma↗
PubMed1983

Dorsal column stimulation in multiple sclerosis: effects on bladder and long term findings.

The effect of dorsal column stimulation on bladder function in 15 patients with established multiple sclerosis was analysed by urodynamic tests. Significant improvement in flow rate and urethral sphincter pressure was recorded in about two thirds. Of 31 patients examined over five years only 13 showed initial benefit from stimulation and were given permanent stimulators; of these, only three appeared to receive lasting benefit. Early complications occurred in nine patients and five had a relapse of their disease. These results suggest that at present stimulation of the dorsal column does not have a place in the routine management of multiple sclerosis.

Adult↗
PubMed1983

In vivo disturbance of the oxidative metabolism of glucose in human cerebral gliomas.

Abnormalities in the oxidative metabolism of glucose in human cerebral gliomas have been studied in seven patients using positron emission tomography. Measurements of regional cerebral blood flow and oxygen consumption were obtained using the oxygen-15 steady-state inhalation technique. Values of regional cerebral glucose consumption were obtained using fluorine 18-labeled 2-fluoro-2-deoxy-D-glucose and a simplification of the method of Sokoloff. Functional values were obtained for regions of tumor and brain tissue in the middle cerebral artery territory of the contralateral cortex. Values of regional glucose consumption were calculated for both regions using a value of the lumped constant quoted for normal brain tissue (0.42). Tumor regional cerebral blood flow was comparable to that in the contralateral cortex, whereas regional cerebral oxygen consumption was depressed. This depression resulted in low tumor values of the fractional oxygen extraction ratio (0.21 +/- 0.07), indicating that oxygen supply exceeded the metabolic demand. In contrast, tumor regional cerebral glucose consumption was not depressed and regional glucose extraction ratios were similar for tumor and brain tissue. The metabolic uncoupling between regional oxygen consumption and regional glucose consumption (CMRO2/CMRGlu = 0.24 +/- 0.07 ml of oxygen per milligram of glucose) is indicative of increased aerobic glycolysis.

Adult↗