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Biomedical subjects

D Robertson

Publications and source records attributed to D Robertson.

At least 343 records · Page 19Linked to original sources
PubMed1987

Brainstem organization of efferent projections to the guinea pig cochlea studied using the fluorescent tracers fast blue and diamidino yellow.

Intracochlear injection of the fluorescent retrograde neuronal tracers fast blue and diamidino yellow was used to investigate the distribution within the brainstem of neurones projecting to the cochlea in the guinea pig. The overall pattern of distribution of cells within the brainstem auditory nuclei was the same for both tracers and was also in broad agreement with recent studies in this species using horseradish peroxidase as the neuronal tracer. However, the total number of neurones found (mean of 1234 projecting to each cochlea) was significantly greater than that reported using horseradish peroxidase, largely as a result of more small labelled neurones being detected within the lateral superior olivary nucleus ipsilateral to the injected cochlea. The yield of labelled cells was greatest in animals in which care was taken to perfuse the whole length of the cochlear epithelium. After bilateral injections of both tracers, double-labelled cells were found in small numbers within all the large neurone medial system nuclei and the ventral nucleus of the lateral lemniscus. It was concluded that between 1-5% of the medial system neurones project to both cochleas.

Amidines↗
PubMed1987

Quantitative estimate of bilaterally projecting medial olivocochlear neurones in the guinea pig brainstem.

Bilateral intracochlear injections of the fluorescent retrograde neuronal tracers fast blue and diamidino yellow were used to identify efferent neurones in the guinea pig brainstem which project to the inner ear on both sides. Bilaterally projecting neurones, detected by their double-labelled appearance in fluorescence microscopy, were found in all the nuclei of origin of the large neurone extra-LSO system of olivocochlear neurones. No double-labelled neurones were found in the small neurone LSO system. When precautions were taken to maximize their capture, these bilaterally projecting neurones comprised 5.4% of the total extra-LSO system neurones projecting to any one cochlea. On the basis of these quantitative data, it was suggested that the bilaterally projecting neurones may correspond to the small group of binaurally activated cochlear efferents identified in physiological studies.

Amidines↗
PubMed1987

Segregation of efferent projections to different turns of the guinea pig cochlea.

Localized intracochlear injections of the fluorescent retrograde label diamidino yellow were used to investigate the organization of efferent projections from the brainstem to different turns of the cochlea, in the guinea pig. It was found that the location of small neurones within the lateral superior olive ipsilateral to the injection varied in a systematic manner when injections proceeded from base to apex of the cochlea. In addition, a cruder form of cochleotopic organization was present in that most of the large medial system efferent neurones were labelled only after injection into the 3 most basal turns of the cochlea. The decline of medial system efferent innervation proceeding from base to apex was most striking for the contralateral efferent neurones. The details of base to apex innervation density were different for the different nuclei of origin of the medial system, implying the existence of complex subsystems within the medial neurone population.

Animals↗
PubMed1987

Food allergy and intolerance.

In summary, there has been a dramatic increase in our understanding of food allergy as a result of research in immune mechanisms and clinical studies over the last decade. The subject has been comprehensively reviewed in a major new publication (Brostoff and Challacombe, 1986).

Antibody Formation↗
PubMed1987

Biological properties of a tumour cell line (NB1-G) derived from human neuroblastoma.

The properties of a new tumour cell line (NB1-G) derived from human neuroblastoma by xenografting in nude rats followed by adaptation to tissue culture are described. Studies using a panel of monoclonal antibodies demonstrate the neuro-ectodermal nature of the cells and support the diagnosis of the primary tumour as neuroblastoma. Cytogenetic studies have revealed a human karyotype with several chromosomal abnormalities. Genetic analysis by in situ DNA hybridization has demonstrated the presence of multiple copies of the N-myc gene. Approximately 20-30 fold amplification of the gene is observed on Southern blot analysis. The cell line has been adapted to growth as multicellular tumour spheroids as well as monolayer culture. Radiobiological studies on spheroids show the cells to be radiosensitive with low capacity for sub-lethal damage accumulation and repair. The cell line should be useful for fundamental studies of human neuroblastoma as well as experimental therapy in vitro.

Animals↗
PubMed1987

Cloning of human thymic subcapsular cortex epithelial cells with T-lymphocyte binding sites and hemopoietic growth factor activity.

The thymic microenvironment involves complex cell interactions among different types of epithelial cells, macrophages, tissue histiocytes, and immature and maturing T cells. We describe the isolation of a subset of thymic epithelial cells by selective primary culture followed by cotransfection with a simian virus 40 replication-origin-defective mutant and pSV2neo plasmid. The cloned cells have the composite immunophenotype that is unique to thymic subcapsular epithelial cells, suggesting that they may provide a model system in vitro for analyzing the earliest steps in T-cell differentiation. This possibility is supported by the finding that these epithelial cells express LFA-3-associated binding sites for T cells, secrete a macrophage hemopoietic growth factor, and synergize with macrophages in the production of interleukin 1.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1987

Ultrastructural, immunocytochemical, and cytogenetic characterization of a human epithelioid sarcoma cell line (RM-HS1).

A cell line (RM-HS1) derived from a human epithelioid sarcoma was established in tissue culture. Ultrastructurally, the cells show features of those found within the primary tumor. A mixed mesenchymal-epithelial phenotype, defined by reactivity with antibodies to epithelial membrane antigen and to vimentin and keratin intermediate filaments, was found in the tumor, and a similar phenotype persisted in the cultured cells. Cytogenetic analysis revealed a mode of 66 chromosomes. With the use of a variety of banding techniques together with in situ hybridization of a 3H-labeled molecular probe for 18s and 28s ribosomal RNA genes (pX1r101), the karyotypes were shown to contain extensive numerical and structural rearrangements, with up to 24 marker chromosomes.

Adult↗
PubMed1987

Ultrastructure and immunoelectron microscopy of human T-cell leukaemia virus type I-producing lymphoid and non-lymphoid human tumour cells.

The ultrastructure and distribution of some viral and cellular antigens was examined in lymphoid C91/PL and fibroblastic HOS/PL cells infected with human T-cell leukaemia virus type I. Tubuloreticular structures in the endoplasmic reticulum, characteristic of virus-infected or interferon-treated cells, were found in both cell types. Virions were observed particularly in the HOS/PL cells in budding and mature forms and in coated pits, coated vesicles and lysosomes, indicative of receptor-mediated endocytosis. Using immunogold indirect labelling, viral antigens, recognized by sera of infected patients and by monoclonal antibody, were detected in patches on the cell surface and in material loosely attached to the envelope of some virions. Beta 2-microglobulin was associated with virion envelopes from C91/PL and HOS/PL cells, but major histocompatibility complex class 1 (HLA) antigens were not associated with virions even when produced by HLA-positive HOS/PL cells.

Antigens, Surface↗
PubMed1987

Patterns of acid reflux in complicated oesophagitis.

Oesophageal manometry and 24 hour ambulatory pH recordings from the distal oesophagus were carried out in 25 patients with complications of oesophagitis (stricture, Barrett's oesophagus or oesophageal ulcer) and compared with 25 patients with uncomplicated oesophagitis. Acid reflux was more severe in the complicated group with 26.2% of time below pH 4 compared with 11.3% in uncomplicated patients (p less than 0.01). This difference was most marked at night, when complicated patients had long periods of acid reflux with 35.6% time less than pH 4 compared with 5.2% uncomplicated (p less than 0.001). The mean duration of nocturnal acid reflux was 15.4 minutes (2.1 minutes uncomplicated, p less than 0.001). Oesophageal motility was markedly abnormal in all groups, but with no demonstrable differences in lower oesophageal sphincter pressure or peristalsis between the groups. Patients with complications of oesophagitis have different patterns of acid reflux from uncomplicated patients, with prolonged nocturnal bathing of the oesophageal mucosa, which may be the cause of stricture formation, metaplasia, or ulceration.

Adolescent↗
PubMed1987

Neck tumour with syncope due to paroxysmal sympathetic withdrawal.

A patient with recurrent squamous carcinoma metastatic to the neck after radical neck dissection and high dose radiation therapy developed paroxysmal hypotensive episodes that were severe, spontaneous and characterised by suppressed sympathetic but not enhanced parasympathetic activity. Intravenous pressors were successful in treating acute episodes but neither drug therapy nor surgical neck exploration reliably prevented syncopal attacks. Glossopharyngeal and/or vagal nerve infiltration by tumour with episodic activation of the afferent limb of the baroreflex arc producing vasodilatation primarily due to sympathetic withdrawal is the likely mechanism of life threatening syncope in this patient.

Adrenergic Fibers↗
PubMed1987

Lines of the pharynx.

This superbly illustrated article is an invaluable guide to the interpretation of double contrast pharyngograms.

Barium Sulfate↗
PubMed1987

Cardiovascular and respiratory effects of adenosine in conscious man. Evidence for chemoreceptor activation.

The cardiovascular and respiratory effects of intravenous adenosine were studied in conscious normal volunteers. Bolus injections of adenosine increased systolic and diastolic pressures initially (+15 and +13 mm Hg after 100 micrograms/kg) followed by a subsequent reduction in systolic and diastolic pressures (-12 and -16 mm Hg). Heart rate increased during trough blood pressure (R-R interval shortening of 298 msec after 100 micrograms/kg). Adenosine steady-state infusions increased heart rate (+30 beats/min during 140 micrograms/kg/min), systolic pressure (+16 mm Hg), and pulse pressure (+21 mm Hg) but decreased diastolic pressure slightly (-5 mm Hg), resulting in no significant change in mean arterial pressure. Adenosine stimulated respiration, resulting in decreased PaCO2 (41 to 31 mm Hg), increased PaCO2 (101 to 113 mm Hg), and increased pH (7.42 to 7.50). The increased ventilation was not explained by bronchoconstriction, hypotension, or hypoxia. The observed pressor and tachycardic effects are mediated through reflex autonomic mechanisms since they are completely abolished in patients with severe autonomic failure. These autonomic mechanisms probably involve chemoreceptor activation since adenosine is pressor when infused in the aortic arch proximal to the origin of the carotid arteries but depressor when infused in the descending aorta. It is concluded that the hemodynamic and respiratory effects of adenosine observed in normal volunteers are in part due to chemoreceptor stimulation. These findings raise the possibility that adenosine is an endogenous modulator of respiration in man.

Adenosine↗
PubMed1987

Angiotensin II-noradrenergic interactions in renovascular hypertensive rats.

This study tested the hypothesis that interactions of endogenous angiotensin II (AII) with the noradrenergic neuroeffector junction are important in renin-dependent hypertension. In the in situ blood-perfused rat mesentery, in normal rats exogenous AII potentiated mesenteric vascular responses to periarterial (sympathetic) nerve stimulation (PNS) more than vascular responses to exogenous norepinephrine (NE). In 2-kidney-1-clip (2K-1C) rats with renovascular hypertension mesenteric vascular responses to PNS and NE were greater than in sham-operated rats, and renovascular hypertension mimicked the effects of exogenous AII with respect to enhancing responses to PNS more than responses to NE. In 2K-1C rats, but not in sham-operated rats, 1-Sar-8-Ile-AII markedly suppressed vascular responses to PNS, without influencing responses to NE. Finally, 1-Sar-8-Ile-AII attenuated sympathetic nerve stimulation-induced neuronal spillover of NE in 2K-1C rats, but not in sham-operated rats. These data indicate that renovascular hypertension enhances noradrenergic neurotransmission, and that this enhancement is mediated in part by AII-induced facilitation of NE release.

Angiotensin I↗
PubMed1987

Oral yohimbine in human autonomic failure.

Yohimbine is an alpha 2-adrenoreceptor antagonist that acts to enhance sympathetic nervous system discharge and potentiate sympathetically mediated cardiovascular reflex responses. We therefore assessed the ability of yohimbine to increase sympathoadrenal discharge and raise blood pressure (BP) in patients with autonomic failure characterized by profound orthostatic hypotension. Yohimbine 5 mg orally in eight seated patients significantly elevated mean systolic BP by 33 mm Hg from 136 +/- 15 (mean +/- SD) to a maximum of 169 +/- 23 mm Hg (p less than 0.01), mean diastolic BP by 16 mm Hg from 77 +/- 9 to a maximum of 93 +/- 15 mm Hg (p less than 0.01), and mean heart rate (HR) by 10 beats per minute (BPM) from 68 +/- 12 to a maximum of 78 +/- 17 BPM (p less than 0.01). Plasma norepinephrine (NE) increased from 104 +/- 71 to a maximum of 196 +/- 182 pg/ml (p less than 0.05), but plasma epinephrine (E) did not increase significantly (31 +/- 18 versus a maximum of 39 +/- 21 pg/ml). In five patients given yohimbine 2.5 mg orally, BP, HR, NE, and E tended to increase, but the changes were not significant. Plasma yohimbine levels correlated significantly with the changes in mean arterial pressure (r = 0.61, p less than 0.01). Yohimbine raises BP and HR in patients with autonomic failure. These effects are dose- and concentration-dependent and mediated through increased sympathetic discharge. Yohimbine may be useful in the treatment of orthostatic hypotension associated with autonomic failure. It is unique among current modes of therapy for this disorder in that it enhances discharge of the patient's own sympathetic system.

Administration, Oral↗
PubMed1987

Tissue staining properties of lectins from the seeds of the jack fruit (Artocarpus integrifolia) and the winged bean (Psophocarpus tetragonolobus).

N-acetyl-D-galactosamine binding lectins from winged bean (Psophocarpus tetragonolobus) and jack fruit (Artocarpus integrifolia) were isolated, purified and conjugated with horse radish peroxidase and their tissue staining properties studied. Despite having an apparently common inhibiting sugar, the lectins showed differences in their staining properties. The lectin from the winged bean stained none of the mouse and human tissues tried even after neuraminidase treatment whereas the jack fruit lectin stained most of the untreated cells. The staining was found to be improved by the prior treatment of the cells with neuraminidase and inhibited completely by the inhibiting sugar. The differences in the staining properties of the lectins are discussed.

Animals↗