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Biomedical subjects

R Slater

Publications and source records attributed to R Slater.

At least 91 records · Page 5Linked to original sources
PubMed1985

Neuroepithelioma (neuroblastoma) arising in an adult. A case report.

Cytogenetic studies on neuroblastomas arising in children have revealed consistent abnormalities of the short arm of chromosome number 1. Partly because of the rare occurrence of neuroblastomas in adults, extensive cytogenetic studies in this group of patients have not been performed. We report a case of a neuroepithelioma (neuroblastoma) arising in a 50-year-old male patient. On chromosome analysis of a metastasis, a stemline with karyotype 47,XY, +der1 (1 qter---1 cen::1q21---1 qter) was identified. The possible consequences of this result and those of results previously reported in the literature are discussed.

Chromosome Aberrations↗
PubMed1985

Hybridization of N-acetoxy-N-acetyl-2-aminofluorene-labelled RNA to Q-banded metaphase chromosomes.

This paper describes improvements of a recently developed immunocytochemical method for the detection of specific polynucleotide sequences within chromosomes, as well as conditions by which this method can be combined with chromosome banding. The immunocytochemical method involves modification of polynucleotide probes with N-acetoxy-N-acetyl-2-aminofluorene (AAAF)2), and hybridization of the modified probes with metaphase chromosomes; the hybrids are made visible immunocytochemically by means of an antiserum which recognizes AAAF-induced polynucleotide modifications. We have sorted out conditions which allow a high sensitivity of hybrid detection by the above procedure, in combination with chromosome banding. The best results are obtained if the ABC-technique is used for the visualization of the hybrids; the lower limit of detection is estimated to be a sequence of about 7000 nucleotides. The method can be combined with Q-banding of chromosomes, if this is performed not more than 1 day prior to hybridization, and if excitation of the Q-banded chromosomes is kept to a minimum.

2-Acetylaminofluorene↗
PubMed1983

[3H]etorphine binding in rat striatum following lesions of the raphe nuclei.

Following 5,7-dihydroxytryptamine lesions of the rat raphe nuclei a significant reduction in striatal serotonin concentrations was observed. However, with [3H]etorphine as ligand no change in opiate receptor binding was observed in striatal membranes. Moreover, when [3H]etorphine binding was resolved into its mu- and delta + kappa-components no change in either component was observed compared with controls. It is concluded that opiate receptors are not on striatal serotonergic nerve terminals whose cell bodies are located in the raphe nuclei.

5,7-Dihydroxytryptamine↗
PubMed1983

Identification and biological activity of tamoxifen metabolites in human serum.

During the examination of serum samples from patients on chronic 'Nolvadex' therapy three major metabolites (X, Y and Z) were detected in addition to the parent drug. Two of these metabolites have been positively identified as N-desmethyltamoxifen (X) and a side-chain primary alcohol (Y). The third metabolite (Z) has been tentatively identified as N-desdimethyltamoxifen. Quantitative analysis of these metabolites in sera from patients undergoing chronic Nolvadex therapy (20 mg approximately b.d.) has shown that the mean N-desmethyltamoxifen concentration was 481 ng/ml, the mean metabolite Y concentration was 49 ng/ml and that desdimethyltamoxifen concentrations were in the range 20-40 ng/ml. The corresponding mean unchanged drug level in these patients was 310 ng/ml. 4-Hydroxytamoxifen could not be detected in these samples. Measurements of the relative binding affinities of tamoxifen and its metabolites for rat uterus oestrogen receptors have shown that 4-hydroxytamoxifen had a relative binding affinity similar to oestradiol while tamoxifen and its side-chain metabolites had lower affinities. It has been shown that all the metabolites examined are antioestrogenic, as demonstrated by their ability to prevent implantation in pregnant rats and inhibit oestradiol-induced uterine weight gain. It is therefore possible that the metabolites of tamoxifen collectively contribute to the therapeutic activity of the drug.

Animals↗
PubMed1983

Parametric studies of tinnitus masking and residual inhibition.

A study was made of the relation between tinnitus masker composition (frequency, bandwidth, intensity duration) and the time course and magnitude of residual inhibition (RI). RI was determined by methods of (a) loudness estimation - where the subject varied the pointer position on a loudness scale (b) loudness balance - where the tinnitus loudness was maintained in loudness balance in the period following masking with a tone of variable intensity presented to the opposite ear. In addition, sensitivity change (temporary threshold shift, TTS) in the tinnitus and masker frequency regions was measured by determining tone thresholds (using a tracking technique) before and after masker presentation. The key findings were as follows: (I) RI depends on masker centre frequency. The frequency producing maximal RI is usually lower than the tinnitus frequency (as determined by pitch matching). (2) In some subjects only narrow-band noise produces RI. (3) RI is proportional to the masker intensity provided the tinnitus is completely masked; little or no RI is produced by a partial masker. (4) For the masker durations used (in the range 10 s to 10 min) RI duration is linearly related to the logarithm of masker duration. (5) A second masker presentation during RI does not potentiate RI. (6) Contralateral masking did not produce RI. (7) maskers producing RI also produce TTS around the tinnitus frequency. (8) The TTS magnitude and the time course of TTS appear to be related to RI.

Acoustics↗
PubMed1982

Stereotactic neurosurgery using 3-D image data from computed tomography.

During the last decade computer tomography (CT) scanners have provided images that show internal anatomy of unsurpassed resolution and that, since they are inherently digital, a format computer graphics software can easily process. By combining CT images, a specially designed head-mounted instrument, and the software to coordinate them, improved surgical accuracy can result for stereotactic surgery. Using the head-mounted frame and the interactive computer software described here, the entire stereotactic approach is transportable to computer systems of three major CT manufacturers. Neurosurgeons now have a tool that allows trajectory selection and probe placement entirely within the CT suite. Compared with conventional stereotaxis, the CT-aided approach offers increased accuracy, with a significant fluid contrast injection for finding reference points and the avoidance of important brain structures due to the direct visualization afforded with CT. Key interactive features are shown here that allow unrestricted views of anatomy in the area of surgical interest. For example, oblique views that are normal to the trajectory of neurosurgical instruments are extracted in real time during the surgical procedure. Standard sagittal (lateral) and coronal (frontal) image planes are also shown integrated with the interactive technique. The surgical procedure is outlined and details of the pattern recognition technique for image-to-frame registration are presented. Test, phantom, and patient results are given.

Brain↗
PubMed1979

Benign recurrent vertigo.

Patients with recurrent vertigo in the absence of cochlear signs remain a diagnostic problem. The absence of a standard system of nomenclature further hampers the understanding of these disorders. The term benign recurrent vertigo is suggested as a useful term to characterise many of these patients. The disorder shares some of the features of migraine, and seems likely to have a similar vasospastic aetiology.

Adult↗
PubMed1979

The quality of verbal interaction in homes for old people.

Some 4,500 verbal exchanges among residents, and between staff and residents were recorded during structured observations in eight British purpose-built Homes for old people. These interactions were initially categorised as 'supportive/acceptive' or as 'other'. Subsequently, the 'other' data from four of the Homes was further classified as 'instrumental' and 'unclassifiable'. The participants in the exchanges were noted (resident or staff) as was the mental status assigned to residents ('confused' or 'rational'). The data suggest that interactions among residents are more likely to be supportive/acceptive than are those between staff and residents; that, similarly, interactions among rational residents are more likely to be supportive than those between rational and confused residents, or than those among confused residents. Interactions between rational and confused residents are more likely to be supportive than those among confused patients. Further, the data indicate that interactions between staff and rational residents, and between staff and confused residents do not differ in quality; predominantly, interactions between staff and residents are instrumental. These interpretations of the data are discussed in relation to the care of residents in institutional settings.

Aged↗
PubMed1978

Alterations in regional cerebral hemodynamics and metabolism produced by focal cerebral ischemia.

Since diffuse changes in blood flow and metabolism occur in the brain following a focal ischemic insult, changes of cerebral blood flow on the side opposite a cerebral infarction were observed. We have examined the course of the cerebral hemodynamic changes occurring in 15 patients with unilateral acute strokes. In 12 of these patients, significant blood flow changes (over 15%) occurred in the nonischemic hemisphere during the period of observation. A similar time course of change was found in the ischemic hemisphere and the flow changes in the two hemispheres appeared parallel to one another (diaschisis). Thus we have demonstrated a significant reduction in flow in the contralateral cortex following a unilateral ischemic insult. This reduction in flow was of the order of 38% from the control value which agrees quite well with the reduction in cortical glucose consumption of the order of 31%. We postulate that these changes are the hemodynamic and metabolic concomitants of diaschisis and may in part be due to a transneuronal depression of function.

Animals↗
PubMed1977

Radionecrosis of the brain presenting as a mass lesion: a case report.

A case of radionecrosis of the brain in a patient previously treated for squamous cell carcinoma of the scalp is presented. Cerebral angiography revealed a mass effect primarily in the right frontal area. Computed tomography showed extensive hemispheric oedema. A frontal lobectomy was performed, and the recovery was excellent. The lower limit for brain tolerance for irradiation is about 5000 rads given in five weeks. This dose should not be exceeded when extracranial lesions are treated. Although computed tomography cannot diagnose brain necrosis, specifically, it should, along with the clinical history, be very helpful.

Brain↗
PubMed1977

Architectural design: the spatial location and interactions of old people.

Residents' interactions in the sitting spaces of purpose-built Homes for old people were studied by participant and structural observation. Eight Homes were sampled from a larger number to represent factors of size (large and small), design (institutional and family) and mental designation of residents (confused or rational). Verbal exchanges between residents were analysed in terms of initiators' and respondents' mental designations. The residents' locations within the sitting spaces and in the sleeping and dining areas of the Homes were recorded. Examination of these data suggests that residents of different mental designations are segregated from each other. Some architectural design elements of physical settings that might foster integration are outlined.

Aged↗