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Biomedical subjects

M Donaghy

Publications and source records attributed to M Donaghy.

63 records · Page 4Linked to original sources
PubMed1983

Cigarette smoking and lung haemorrhage in glomerulonephritis caused by autoantibodies to glomerular basement membrane.

The smoking habits of 51 patients with glomerulonephritis caused by autoantibodies to the glomerular basement membrane (GBM) were investigated. 43 patients also had pulmonary haemorrhage; 8 did not. A full smoking history was obtained from 47 patients. Of these, all 37 cigarette smokers suffered lung haemorrhage, compared with only 2 of 10 non-smokers. There was no significant difference between the titres of circulating anti-GBM antibodies in smokers and non-smokers. In 1 patient resumption of smoking was closely followed by recrudescence of lung haemorrhage. These results largely explain the variable presence of pulmonary haemorrhage in anti-GBM disease.

Adolescent↗
PubMed1983

Studies of cellular immunity in male homosexuals in London.

97 symptom-free homosexuals were studied clinically, serologically, and with in-vivo and in-vitro tests of cellular immune function in the context of the acquired immunodeficiency syndrome (AIDS). A high proportion of these men showed abnormalities: lymphopenia (33%), decreased T-helper/T-suppressor (Th/Ts) cell ratios (43%), both these abnormalities (12%), decreased total T-helper cells (15%), monocyte chemotactic (10%) and phagocytic (27%) defects, anergy to three recall antigens (32%), and anergy to purified protein derivative despite BCG inoculation (55%). The lymphocyte abnormalities and anergy characteristic of AIDS were seen in 5%. No clear clinical or serological associations were seen for the AIDS-like defects. Trends of association were seen between higher lymphocyte counts, lower Th/Ts ratios, more T-suppressor cells and serological evidence of previous virus infection. The combination of lymphocyte abnormalities and anergy observed in these symptom-free homosexuals may represent a latent phase of AIDS.

Acquired Immunodeficiency Syndrome↗
PubMed1983

Cerebral blood flow studies with 123iodine-labelled amines.

The cerebral distribution of a new class of 123I radiopharmaceuticals was determined by emission tomography after the isotope had been injected intravenously into 20 patients with a variety of neurological disorders. Regional cerebral blood flow images of diagnostic quality were obtained in all cases. Early and late ischaemic stroke showed up as areas of impaired perfusion, and gliomas and secondary deposits as areas of increased or reduced blood flow. A hyperaemic focus was clearly seen in an epileptic patient in whom other imaging techniques, including CT scanning and electroencephalography, had been uninformative. This new technique promises to be an extremely useful addition to the range of radioisotope brain scanning methods.

Adult↗
PubMed1983

Defective monocyte function in pyoderma gangrenosum with IgG kappa paraproteinaemia.

Peripheral blood monocytes from a patient with pyoderma gangrenosum and paraproteinaemia showed defective phagocytosis; longitudinal observations demonstrated an association between the defect, the level of paraprotein and the clinical activity of the pyoderma. Treatment with Melphalan led to a reduction in the paraprotein level and remission of the pyoderma and was accompanied by normalization of monocyte function. After 8 months remission the paraprotein level rose again and was accompanied by a recurrence of the monocyte defect; shortly after this the pyoderma recurred. Pre-incubation of normal monocytes with the patient's plasma or immunoglobulin fractions revealed that a similar defect could be induced in normal cells by the patient's monomeric IgG. The patient's serum also had anti-heparin activity and the relationship between this and the phagocytic defect was explored. These studies indicate a possible pathogenetic mechanism underlying the association between pyoderma gangrenosum and monoclonal gammopathy.

Aged↗
PubMed1980

Integration of visual and auditory space in the mammalian superior colliculus.

Recordings of eye movements and single-neurone microelectrode recordings of the superior colliculus in cats show that, for each saccadic movement, their eyes start near to the centre of the orbit so that the coordinates of visual and auditory space are aligned, and complex neural compensation of auditory or visual inputs to the superior colliculus is unnecessary.

Animals↗
PubMed1980

Co-ordination of head and eyes in the gaze changing behaviour of cats.

1. Saccadic changes of gaze have been studied in conscious cats implanted with electro-oculographic electrodes to register eye position and held in a device for measuring head position.2. When the head is free to move, almost all saccades larger than 4 deg in amplitude are accompanied by head rotation. This head movement starts at a variable delay after the beginning of the eye movement. Most frequently, the latency is 30 msec.3. After finishing its saccade, the eye rotates retrogressively in the orbit so as to maintain a constant direction of gaze during the remaining portion of the head movement. This compensatory eye movement has an average gain of 0.96 in the absence of visual feed-back.4. The duration and peak velocity characteristics of head-fixed saccades were measured. A typical horizontal saccade of 20 deg in amplitude attains a peak velocity of 250 deg/sec and lasts 110 msec. The duration-amplitude relationship increases by 2.1 msec/deg.5. Saccades aimed obliquely within the orbit possess the same duration/peak-velocity/amplitude relationships as purely horizontal saccades. Consequently, the horizontal component of an oblique saccade lasts longer, and has a lower peak velocity, than a purely horizontal saccade of the same amplitude as this component. This finding is discussed in relation to brain-stem control of oblique saccades.6. A saccade is initially programmed to achieve the desired gaze change without aid from the head. Consequently, the saccade is slowed down so as to prevent gaze overshoot when the head moves too. Since this saccadic attenuation occurs even during passive head movement, it must be due to feed-back from peripheral sensors of head rotation, and probably represents the initial stage of the compensatory eye movement.7. Since the axes of horizontal head and eye rotation are horizontally separated, it may be predicted that the gain of compensatory eye movements must rise as the viewing distance decreases if they are to maintain fixation during head movements. This prediction was confirmed.

Animals↗
PubMed1980

The cat's vestibulo-ocular reflex.

1. The conscious cat's vestibulo-ocular reflex (v.o.r.) has been studied using the electro-oculogram to measure eye movements. A servomotor was used to rotate the head horizontally while the body remained stationary. 2. The frequency content of natural head movements in the cat has been determined by Fourier analysis. The fastest and most kinked head movement profiles contain frequency components of significant power extending up to 7-10 Hz. 3. The transfer function of the v.o.r. slow-phase response was measured in the frequency range 0.2-7 Hz. At 1 Hz the average gain is 0.94 with a phase lead of 3 deg. At 7 Hz the gain has only fallen to 0.81 and the phase lag is 10 deg. This indicates that the v.o.r. can compensate to a considerable degree for the high-frequency components of natural head movements. 4. Rotation of the body around a stationary head in the absence of vision does not produce a measurable neck-ocular reflex. 5. The presence or absence of fast phases has no effect on the phase lead of the v.o.r. slow-phase response at 0.2 Hz. 6. V.o.r. fast phases never occur more frequently than 4/sec. 7. Fast phases do not function merely to recentre the eyes once a slow phase has driven them to extreme orbital eccentricities. Instead, fast phases occur early on and serve to offset gaze in the same direction as the head movement.

Animals↗
PubMed1980

The contrast sensitivity, spatial resolution and velocity tuning of the cat's optokinetic reflex.

1. Optokinetic nystagmus has been evoked from two cats using horizontally moving vertical grating patterns with sinusoidally modulated wave forms (mean luminance 8.5 cd/m2). Eye movements were recorded by DC electro-oculography. 2. The velocity 'tuning' of the slow phase response was measured for high-contrast (0.8) gratings with spatial frequencies ranging from 0.18 to 2.8 cycles/deg. Irrespective of spatial frequency, the gain of slow phase tracking always declined as the stimulus velocity exceeded 5-8 deg/sec. 3. The effect of variations in grating contrast on the gain of slow phase tracking was investigated for spatial frequencies ranging from 0.04 to 2.8 cycles/deg. These gratings always moved at a velocity of 3 deg/sec. Reductions in grating contrast produced a fall in the gain of slow phase tracking. At any given contrast, the extent of the fall in gain depended on spatial frequency. At no value of spatial frequency was an optokinetic response demonstrable when the contrast fell below 0.02. 4. The above results have been used to derive the threshold contrast for evoking an optokinetic response at each spatial frequency tested. A contrast sensitivity function is plotted from these threshold contrasts, and this is compared with previous estimates of the cat's contrast sensitivity function derived from measurements of visual discrimination and cortical evoked potentials.

Animals↗