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Biomedical subjects

D Doyle

Publications and source records attributed to D Doyle.

At least 181 records · Page 10Linked to original sources
PubMed1979

Tests of prolactin secretion in diagnosis of prolactinomas.

Prolactin-secreting tumours of the pituitary were identified and treated by transsphenoidal microsurgery in fourteen infertile females with hyperprolactinaemia. Resting prolactin levels were 590--9000 mU/1 (mean 3400). In seven patients, tomography of the pituitary fossa was normal and resting prolactin levels were 590-6000 mU/1 (mean 3400). In these patients the pre-operative diagnosis prolactinoma in these patients was made by demonstrating loss of the normal circadian prolactin profile and impaired prolactin response to intravenous thyrotrophin-releasing hormone (T.R.H.) and metoclopramide stimulation. Prolactin response to the acute oral administration of L-dopa and bromocriptine was of less diagnostic value. Preoperative assessment of anterior pituitary function identified abnormalities other than hyperprolactinaemia in four patients (28%). Post-operative assessment indicated that microsurgery was curative in twelve patients (86%), selective in all, and without significant side-effect. It is concluded that dynamic tests such as T.R.H. and metoclopramide stimulation have considerable value in identifying hyperprolactinaemic patients with prolactin-secreting adenomas, particularly those which are radiologically occult.

Adolescent↗
PubMed1979

Effect of trypsin on the cell surface proteins of hepatoma tissue culture cells. Characterization of a carbohydrate-rich glycopeptide released from a calcium binding membrane glycoprotein.

Concentrations of trypsin that bring about aggregation of hepatoma tissue culture (HTC) cells also release from the cell surface an Mr = 55,000 glycopeptide fragment. This glycopeptide fragment also accumulates in the medium, including serum-free medium, as a normal consequence of membrane protein turnover. The trypsin-released glycopeptide is labeled when cells are grown in the presence of fucose or leucine before treatment of the cells with the protease. Similarly, the glycopeptide fragment can be labeled by reacting cells in situ by lactoperoxidase-catalyzed radioiodination or by tritiated borohydride reduction of cells treated first with neuraminidase and galactose oxidase. The tryptic glycopeptide fragment was purified by concanavalin A-Sepharose chromatography, and hydroxyapatite chromatography in the presence of dodecyl sulfate. The amino acid and carbohydrate composition was determined, as was the sensitivity of the purified glycopeptide to a variety of endo- and exoglycosidases. The purified glycopeptide contains an average of 17 sialic acid residues and hence, shows charge heterogeneity after electrophoresis in isoelectric focusing gels. The charge heterogeneity can be eliminated completely by treatment with neuraminidase. The glycopeptide after this treatment is homogeneous. The trypsin-sensitive membrane glycoprotein which is the source of the Mr = 55,000 glycopeptide was identified by two-dimensional gel electrophoretic analysis of labeled cells, treated or not treated with trypsin. This glycoprotein, which has an apparent molecular weight of 85,000 and forms a homodimer in the presence of calcium ions, was purified and its identity as the parent of the Mr = 55,000 glycopeptide was confirmed by showing that the same Mr = 55,000 fragment was released by trypsin from the purified glycoprotein as was released from the intact cells.

Amino Acids↗
PubMed1979

Computerised tomography after recent severe head injury in patients without acute intracranial haematoma.

Sixty patients with severe head injury who did not have an acute intracranial haematoma on CAT scanning are reviewed. The scans are correlated with the level of consciousness at the time of scanning and with the outcome six months after injury. The initial scan was interpreted as being normal in 38% of the cases. In the remainder the most common abnormalities were small ventricles and areas of mixed increased and decreased density interpreted as contusions. All the patients with small ventricles were under 20 years of age. Postmortem examinations were undertaken on 15 of the 19 fatal cases. There was evidence of a high intracranial pressure in 12, cerebral contusions were absent or minimal in 10, there was diffuse immediate impact damage to white matter in six, and there was moderate or severe hypoxic damage in four.

Adult↗
PubMed1978

Purification and characterization of human erythrocyte purine nucleoside phosphorylase and its subunits.

Purine nucleoside phosphorylase (EC 2.4.2.1; purine nucleoside:orthophosphate ribosyltransferase) from fresh human erythrocytes has been purified to homogeneity in two steps with an overall yield of 56%. The purification involves DEAE-Sephadex chromatography followed by affinity chromatography on a column of Sepharose/formycin B. This scheme is suitable for purification of the phosphorylase from as little as 0.1 ml of packed erythrocytes. The native enzyme appears to be a trimer with native molecular weight of 93,800 and the subunit molecular weight of 29,700 +/- 1,100. Two-dimensional gel electrophoresis of the purified enzyme under denaturing conditions revealed four major separable subunits (numbered 1 to 4) with the same molecular weight. The apparent isoelectric points of subunits 1 to 4 in 9.5 M urea are 6.63, 6.41, 6.29, and 6.20, respectively. The different subunits are likely the result of post-translational modification of the enzyme and provide an explanation of the complex native isoelectric focusing pattern of purine nucleoside phosphorylase from erythrocytes. Three of the four subunits are detectable in two-dimensional electrophoretic gels of crude hemolysates. Knowing the location of the subunits of purine nucleoside phosphorylase in a two-dimensional electropherogram allows one to characterize the purine nucleoside phosphorylase in crude cell extracts from individuals with variant or mutant purine nucleoside phosphorylase as demonstrated in a subsequent communication. Partial purification of the phosphorylase from 1 ml of erythrocytes on DEAE-Sephadex increases the sensitivity of detection of the subunits to the 0.3% level.

Erythrocytes↗
PubMed1978

The smear technique in the diagnosis of neurosurgical biopsies.

This paper reviews 216 consecutive neurosurgical biopsies examined by the immediate smear technique, and the smear diagnoses are compared with the final diagnoses made on paraffin processed sections of the same material. Ninety three percent (93%) of the diagnoses were correct. The majority of errors were due to the incorrect classification of malignant tumours. The diagnosis of malignancy, however, was clearly established in all of these cases. The smear technique is suitable for application to material obtained at craniectomy, laminectomy, and also the small, soft pieces of tissue obtained by needle biopsy through a burr hole.

Biopsy↗
PubMed1978

Ischaemic brain damage in fatal non-missile head injuries.

The incidence and distribution of ischaemic brain damage in a consecutive series of 151 patients who died as a result of a non-missile head injury in the Institute of Neurological Sciences was determined on the basis of a comprehensive neuropathological and neurohistological examination. Ischaemic damage was identified in 138 cases (91%) even after excluding cases who only had necrosis and infarction related to contusions or fat embolism, and infarction in the brain stem of the type conventionally associated with raised intracranial pressure. The ischaemic damage was assessed as severe in 37 (27%), moderately severe in 59 (43%) and mild in 42 (30%), and in the 138 cases with ischaemic brain damage it was found more frequently in the hippocampus (122 cases; 81%), and in the basal ganglia (119 cases; 79%) than in the cerebral cortex (70 cases; 46%) and in the cerebellum (67 cases; 44%). There were statistically significant correlations between ischaemic brain damage and either an episode of hypoxia or of raised intracranial pressure. From the nature of the brain damage it seems likely that much of it was due to a reduction in the cerebral perfusion pressure. This study has shown that ischaemic brain damage is common after head injury, that at least a proportion of it is probably avoidable, and that it is more important as a cause of mortality and morbidity after head injury than has been hitherto realised.

Adolescent↗
PubMed1978

Genetics of the large, external, transformation-sensitive (LETS) protein: assignment of a gene coding for expression of LETS to human chromosome 8.

Techniques have been developed to analyze the genetics of the large, external, transformation-sensitive (LETS) protein (fibronectin). External membrane proteins of human-mouse somatic cell hybrids with reduced numbers of human but not mouse chromosomes were labeled by lactoperoxidase-catalyzed iodination. Cell surface proteins were identified after sodium dodecyl sulfate/polyacrylamide gel electrophoresis by autoradiography of the dried gel. The LETS protein was identified in parental human cells, and LETS segregated in human-mouse cell hybrids formed from human WI-38 fibroblasts and a mouse L-cell line not expressing LETS. The LETS protein segregated concordantly with the chromosome 8 enzyme marker glutathione reductase (EC 1.6.4.2) and human chromosome 8. These findings demonstrate that a gene, LETS, encoded on chromosome 8, is responsible for the LETS protein expression in humans. Because LETS has been implicated in tumorigenicity and cellular transformation, it is of interest that rearrangement or modifications in the number of chromosome 8 have been associated with certain forms of cancer.

Animals↗
PubMed1978

Changes in the nuclei of astrocytes following portacaval shunting and portacaval transposition in the rat.

Structural abnormalities are found in the astrocytes of the dentate nuclei of animals after portacaval shunting (PCS). These changes are also found in man in association with portal-systemic encephalopathy. To investigate the relationship between portal-systemic shunting and hepatocellular dysfunction in the pathogenesis of these changes, PCS and protacaval transposition (PCT) were performed in rats. PCT diverts portal blood into the systemic circulation, but retains normal total hepatic blood flow by perfusion with systemic venous blood. Liver function and mass are better preserved than after PCS. Abnormal glial cells were found in 4.03% of animals following sham operation, 13.45% following PCT, and 19.09% following PCS. Both experimental groups differed significantly from control animals, and the number of abnormal cells was significantly higher after PCS than after PCT. These findings are in keeping with the hypothesis that hepatocellular dysfunction plays an important role in addition to portal-systemic shunting in the aetiology of the structural changes in the brain associated with hepatic encephalopathy.

Animals↗
PubMed1977

Diffuse brain damage of immediate impact type. Its relationship to 'primary brain-stem damage' in head injury.

In a neuropathological analysis of 151 fatal non-missile head injuries, there were 19 cases with focal lesions in the dorsolateral quadrant of the brain-stem in the corpus callosum, and histological evidence of diffuse damage to white matter. Eight of these cases had not experienced a high intracranial pressure during life. All 19 cases had been rendered unconscious at the moment of impact and had remained so or in the persistent vegetative state until death. It is therefore concluded that diffuse damage to white matter may occur as a primary event at the moment of impact, that is, it is one type of immediate impact damage to the brain. It is also concluded that this type of damage is the pathological basis of 'primary brain-stem injury' since in no patient thought clinically to have sustained 'primary brain-stem injury' were abnormalities confined to the brain-stem. Since no patient with this type of brain damage recovered consciousness after injury, it is probable that diffuse damage to white matter is the most important single factor governing the outcome in a patient who sustains a non-missile head injury.

Adolescent↗
PubMed1977

Neuroectodermal tumours in the cerebellum in two sisters.

Two sisters, one 5 years and the other 2 years old, with intrinsic tumours of the cerebellum are reported. One of the tumours was interpreted as being a ganglioneuroma with neuroblastomatous change. The other was a desmoplastic medulloblastoma.

Cerebellar Neoplasms↗