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Biomedical subjects

D G Thomas

Publications and source records attributed to D G Thomas.

At least 253 records · Page 14Linked to original sources
PubMed1983

Brain tumours.

Brain tumours are uncommon but not rare. They occur particularly in the young and the middle aged. Rather more than 50 per cent are malignant with poor prognosis in spite of surgery, radiotherapy, and chemotherapy. However, benign brain tumours can in general be cured. Early diagnosis and treatment are important in diminishing the morbidity and mortality rates in the latter group and in providing better palliative management in the former. Advances in neuroradiology, particularly the development of CT, have made early diagnosis possible, given clinical awareness of the syndromes of brain tumour on the part of the physician. New methods of accurate CT-controlled surgery for glioma have also been introduced. Advances in adjuvant methods of radiotherapy, with radiation sensitizers or interstitial implantation, and of chemotherapy by tailoring the drug regimen to an individual patient and by targeting agents specifically to brain tumour, are being sought while the feasibility of fresh modes of immunotherapy has been tested. These developments hold some hope that results for malignant glioma may improve in the forseeable future.

Adenoma↗
PubMed1982

Measurement of regional cerebral blood flow and oxygen utilisation in patients with cerebral tumours using 15O and positron emission tomography: analytical techniques and preliminary results.

Regional cerebral blood flow and oxygen utilisation have been studied in 8 patients with brain tumours using continuous inhalation of C15O2 and 15O2 and positron emission tomography. The methods used to analyse the regional cerebral pathophysiology are presented. A relative uncoupling between oxygen consumption and blood flow was observed in all tumours as indicated by a decreased regional fractional extraction of oxygen (rOER). This suggest that a major proportion of these tumours had sufficient blood supply to meet oxygen metabolic demand. A decrease of blood flow in grey matter was found both in the affected and contralateral hemispheres of the brain. Matched reductions of flow and oxygen utilisation were observed in oedematous tissue.

Aged↗
PubMed1982

The performance of three approximate confidence limit methods for the odds ratio.

The performance of three approximate confidence limit methods for the odds ratio, R, is studied at the 95% level in the unconditional sample space. There are: the method proposed by Cornfield (Proceedings of the 3rd Berkeley Symposium 1956;4:135-48), the logit method with 1/2 corrections first considered by Woolf (Ann Hum Genet 1955;19:251-3), and the test-based method proposed by Miettinen (Am J Epidemiol 1976;103:226-35). Cornfield's method comes closest to attaining the normal confidence coefficient. The logit method typically has actual confidence coefficients somewhat too large with disparate tail areas. The latter is ascribed in part to the enhanced skewness induced by the logit transformation itself. The test-based method has actual coefficients uniformly less than nominal when R not equal to 1. This underestimation is worse in finite samples than Halperin found it to be asymptotically. Although the Cornfield and test-based methods have the same confidence coefficients for R = 1, the test-based method is more likely to cover distant values of R not equal to 1 when in fact R = 1. It is concluded that Cornfield's method without the continuity correction is the preferred approximate method in the unconditional space as, with the continuity correction, it was previously found to be in the conditional space.

Abnormalities, Drug-Induced↗
PubMed1982

Transoral approach to the cervical spine: report of four cases.

The transoral approach to the upper cervical spine is an established but little used route, offering excellent access with good wound healing, to lesions of the bodies of the atlas, axis and upper part of the third cervical vertebra. The authors report four cases which demonstrate the value of the procedure.

Adult↗
PubMed1982

Combined medical and surgical treatment of spinal hydatid disease: a case report.

A case of chronic hydatid disease of the dorsal spine is described. The patient had undergone four previous operations over a 26 year period and had suffered recent further deterioration leading to complete paraplegia. On this occasion she was treated by a combination of drug therapy and surgery. She showed some neurological recovery after a two and a half month interval, without evidence of recurrence. The surgery would not have been feasible without concurrent drug therapy.

Adult↗
PubMed1982

A report of six surgically treated cases.

Six cases of brain-stem hematoma are described. The clinical presentation in these cases was extremely variable. Operative evacuation of the hematoma resulted in immediate improvement in all cases, and a full or nearly full recovery in five. Untreated brain-stem hematoma is probably always fatal, whereas surgical evacuation is effective and safe. The diagnosis of brain-stem hematoma should be considered in any case of brain-stem lesion.

Adolescent↗
PubMed1981

Evoked potentials to auditory probes as indices of cerebral specialization of function--replication and extension.

This study was an attempt to replicate findings from previous work in our laboratory as well as to study the relationship between vertex-referenced and linked mastoid-referenced responses under conditions purported to produce differential hemispheric activation. Auditory evoked potentials were recorded between T4-Cz, T3-Cz, T4-A1A2, and T3-A1A2 to task-irrelevant tone pips superimposed on a baseline condition and on two experimental conditions (verbal and music) hypothesized to differentially activate areas of the left and right cerebral hemispheres. Significant AEP amplitude asymmetries were obtained as a function of the ongoing tasks, replicating our previous findings. Higher amplitude AEPs were recorded from temporal-to-vertex leads from the hemisphere thought to be most involved in the ongoing task. In addition, temporal-linked mastoids placements showed an effect opposite to that seen for the vertex-referenced leads with lower amplitude AEPs occurring from the hemisphere purported to be most activated by the task. Mastoid-referenced placements were also less sensitive to task effects than vertex-referenced placements.

Adult↗
PubMed1981

Characteristics of the urethral pressure profile in flaccid male paraplegics.

Several aspects of urethral function were studied in an attempt to identify the factors causing urinary retention in the flaccid paraplegic patient. The urethral pressure was much higher in all patients at the external sphincter than at the bladder neck. In patients studied sequentially, even from very early following injury, there was little variation in the maximum urethral closure pressure. Radiological studies showed the point of maximal resistance to be distal to the verumontanum. The urethral pressure at this point was largely abolished by phentolamine infusion. There was no variation in the activity of this region with bladder filling or postural change. It is concluded that in flaccid male paraplegics the major component of urethral resistance is constant, adrenergically innervated muscular resistance in the external sphincter region.

Adolescent↗
PubMed1981

Conservative management of vesicoureteric reflux in the congenital neurogenic bladder.

A series of 31 patients with congenital neurogenic bladder in which vesicoureteric reflux was managed conservatively by methods designed to improve voiding function is reported. Satisfactory results, in terms of the appearance of the upper urinary tracts on IVU, were obtained by indwelling urethral catheter, or by alpha-adrenergic blockade, internal urethrotomy or external urethral sphincterotomy; in the case of the last 3 procedures this was accompanied by diminution or resolution of vesicoureteric reflux. Less satisfactory results were obtained by intermittent self catheterisation and in patients managed in this way a case exists for ureteric reimplantation.

Adolescent↗
PubMed1981

Semantic comprehension in infancy: a signal detection analysis.

The purpose of this study was to validate a paradigm by which an infant's comprehension of concrete nouns could be assessed while controlling for (a) response bias, (b) stimulus preference, and (c) maternal cuing. More specifically, we sought to determine whether 11- and 13-month-old infants directed their eye fixations to the referent of an object word said by the mother and to determine whether there was a developmental shift in responding to object words at these 2 ages, as some previous research suggests. Duration of looking at each of 4 corners of an apparatus was measured while the mother (unable to see what the child was doing) uttered a word she felt the infant knew, 1 she felt he/she did not know, and a nonsense word. Analyses based on signal detection theory using "known" words as signal trials and nonsense words as noise revealed that 13-month-olds directed their looking time significantly longer at the referent of the known word when that word was uttered than when the nonsense word was uttered. At neither age did looking at the referent of the unknown word exceed control values. No significant effects were obtained at 11 months of age, nor were there any sex effects.

Discrimination Learning↗