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Biomedical subjects

D A Winfield

Publications and source records attributed to D A Winfield.

At least 55 records · Page 3Linked to original sources
PubMed1988

Epidural granulocytic sarcoma in acute myeloid leukemia with 8;21 translocation.

Three patients with M2 acute myeloid leukemia (AML) in whom cord compression developed due to epidural granulocytic sarcoma are reported and compared with six similar patients described previously. These three cases had 8;21 translocation, t (8;21), in the marrow karyotype and also in the karyotype of granulocytic sarcoma tissue obtained from two of the cases. Treatment with chemotherapy and radiotherapy can be effective, but an emergency laminectomy should be performed if there is rapid neurologic progression.

Adolescent↗
PubMed1988

Methotrexate and bone marrow metaphases.

The efficacy of a methotrexate (MTX) block/thymidine release synchronization technique has been assessed in bone marrow cultures from patients with acute nonlymphocytic leukemia and myelodysplasia. In contrast to cultures of stimulated lymphocytes from normal individuals, no improvement in mitotic index (MI) or metaphase quality could be detected using this technique. Demonstration of an unchanged level of division in bone marrow cultures in the presence of MTX suggests that the technique is unsuitable for synchronization purposes in this tissue. The influence of preincubation prior to MTX exposure and duration of exposure to colcemid on MI and metaphase quality have also been examined.

Adolescent↗
PubMed1988

Ultrastructural features of acute monoblastic leukaemia cells: a multivariate morphometric analysis.

Morphometric studies were carried out on five ultrastructural measures of size or quantity of some of the intracellular organelles in monoblasts obtained from six patients diagnosed as having acute monoblastic leukaemia and also on monocytes from six normal controls. The morphometric measures were analysed using a one way multivariate analysis of variance (MANOVA) to see whether acute monoblastic leukaemic cells differed from those of normals. It was found that there was a highly significant decrease both in the surface to volume ratio of mitochondria and also in the surface to volume ratio of the nucleus. The possible physiological significance of these structural changes is stressed.

Adult↗
PubMed1987

Atypical bullous pyoderma gangrenosum associated with myeloid malignancies.

Atypical bullous pyoderma gangrenosum was diagnosed during the course of a myeloid malignancy in three patients. One patient had chronic myeloid leukaemia, one acute myeloid leukaemia, and the third, refractory anaemia with excess of blasts. This atypical form of pyoderma gangrenosum has been specifically associated with myeloid malignancies. The atypical appearance of the skin lesions and the clinical context in which they arose caused the true diagnosis to be delayed in all cases. Treatment with steroids was associated with rapid healing of the skin lesion. The histopathological changes in the skin biopsy specimens from these cases were non-specific, and although the histology was considered to be atypical of pyoderma gangrenosum in one case, the unusual features could be attributed to the patient's neutropenia. (Skin biopsy was performed to exclude other specific pathology). Atypical bullous pyoderma gangrenosum is an uncommon association of the myeloid malignancies. It may remain unrecognised and should be considered more often.

Adult↗
PubMed1985

The effect of visual deprivation upon the basal dendrites of Meynert cells in the striate cortex of the monkey.

The basal dendrites of Meynert cells in the striate cortex have been studied with the Golgi method in the brains of monkeys that had been reared for varying periods with the eyelids closed over one eye. The lengths and arrangement of the dendrites were compared with those in normal brains. In the visually deprived brain almost half of the cells had basal dendrites that were apparently normal with the dendritic fields in the form of an ellipse and the long axes parallel to the direction of the ocular dominance bands. The other cells had dendritic fields that have rarely been seen in normal material and two distinct types could be recognized. The 'lop-sided' cell had an ellipsoidal dendritic field with the major axis parallel to the ocular dominance bands, but the extents of the dendrites along the minor axis were very asymmetric; the ratio of the means of the long and short arms of the minor axis of the 'lop-sided' cell is 2.3:1 compared with 1.1:1 in normal brains. The 'perpendicular' type of cell also had an ellipsoidal dendritic field but the relation of the major and minor axes to the direction of the ocular dominance bands was the reverse of the normal cell, with the long axis of the ellipse being aligned perpendicular to the bands. 'Lop-sided' cells formed approximately 18% of the total of Meynert cells studied and the 'perpendicular' 32%. The proportion of the cells with abnormal basal dendritic fields, and particularly the 'perpendicular', increased with longer durations of eyelid closure. It is suggested that the alterations in the dendritic fields of the 'lop-sided' and 'perpendicular' cells may be correlated with the changes in width of the ocular dominance bands that are known to occur after monocular eyelid suture.

Age Factors↗
PubMed1985

Malignant inflammatory fibrous histiocytoma of bone and acute lymphoblastic leukaemia.

A patient is described who developed a malignant inflammatory fibrous histiocytoma of vertebral bone (MFH) 4 months after the onset of acute lymphoblastic leukaemia. This is the first report of the simultaneous occurrence of these two conditions. Similarities to the more frequent occurrence of another histiocytic malignancy, histiocytic medullary reticulosis, following acute lymphoblastic leukaemia, are noted. The usefulness of gallium scanning to monitor the response of this tumour to treatment is demonstrated.

Acute Disease↗
PubMed1984

The platelet defect in acute myeloid leukaemia.

In a study of platelets from 13 patients with acute myeloid leukaemia abnormal aggregation and release reactions were found. A previously unrecognised quantitative defect of thromboxane B2 production may, at least in part, explain these findings. In contrast to a previous report, we were unable to show a convincing storage pool defect in these platelets. The platelet membrane glycoproteins were largely normal.

Adenosine Diphosphate↗
PubMed1983

Laminar cell counts and geniculo-cortical boutons in area 17 of cat and monkey.

Counts have been made of the number of cells in individual laminae of the cortex in area 17 of the macaque monkey and cat, and degenerating terminals of geniculo-cortical axons have been studied with the electron-microscope in laminae IVab and IVc of the cortex of area 17 and lamina IV of area 18 of the visual cortex of the cat. The increase in number of cells through the depth of cortex in area 17 of the monkey compared with the cat would appear to involve about equally all laminae. In lamina IVab of area 17 of the cat the axon terminals of Y-type geniculo-cortical fibres make many more synapses per bouton than those of X-type fibres ending in lamina IVc. The geniculo-cortical axons ending in lamina IV of area 18 also make more multisynaptic boutons than those in lamina IVc of area 17. Thus, the terminals in the cortex of the X and Y functional types of fibre show comparable differences in both the cat and monkey.

Animals↗
PubMed1983

The basal dendrites of Meynert cells in the striate cortex of the monkey.

A study has been made of the basal dendrites of Meynert cells in the striate cortex of the macaque monkey in sections parallel to the pial surface impregnated by the Golgi technique. The longest basal dendrite observed extended up to 0.6 mm and the average length of the longest dendrite on each cell was about 0.28 mm. In general, the dendritic field was in the form of an ellipse with mean major and minor axes of 0.22 mm and 0.11 mm respectively, and encompassing an area of about 0.13 mm2. The directions of the major axes were perpendicular to the lunate sulcus in the sections adjacent to the lunate sulcus, and parallel to the horizontal meridian in sections taken from the region of the representation of the meridian, suggesting that the basal dendritic fields are orientated in parallel with the directions of the ocular dominance bands.

Animals↗
PubMed1983

The postnatal development of synapses in the different laminae of the visual cortex in the normal kitten and in kittens with eyelid suture.

The postnatal development of synapses in the different laminae of the visual cortex has been studied in normal kittens and in kittens with unilateral or bilateral eyelid suture. In general, in normal kittens all laminae underwent basically the same two phases of development as for the cortex as a whole: an initial rapid rise to a peak at about 70 days of age, followed by a reduction in the density of asymmetric axospinous synapses towards the adult levels. There was no indication of a significant reduction in any other type of synapse. Lamina IV did not appear to have a peak density at 70 days of age, but there was a gradual decline after this age in the synaptic density toward adulthood, as for other laminae. The effects of eyelid suture were different for each lamina. On average, the density of synapses in the supragranular laminae underwent an initial retardation in the rate of development followed by a rise to a higher than normal peak at 70 days, and then a fall to below normal adult levels. The infragranular laminae also underwent an initial reduced rate of growth and never acquired their normal adult levels. Lamina IV was the least affected. Much of the changes in the development of synapses involved asymmetric axo-spinous synapses, with a small reduction in the number of symmetric synapses chiefly in lamina IV.

Animals↗
PubMed1982

A quantitative study of the complex laminated body in the lateral geniculate nucleus of the cat.

A quantitative study has been made of the proportions and distribution of cells with complex laminated bodies (CLBs) in the lateral geniculate nucleus of the cat. They develop between 55 and about 70 days postnatal and are distributed irregularly across the medio-lateral extent of lamina A. There was no indication that the proportion of cells with CLBs is higher in the region of lamina A where the area centralis is represented, but the proportion in the binocular segment as a whole was higher than for the monocular segment. In kittens reared with unilateral or bilateral eyelid suture the proportions of cells with CLBs was above normal in the deprived laminae and below normal in the undeprived laminae.

Animals↗
PubMed1982

The termination of geniculocortical fibres in area 17 of the visual cortex in the macaque monkey.

The termination of geniculocortical fibres within the different subdivisions of lamina IV in area 17 of the visual cortex of the monkey has been studied quantitatively with the electron microscope. In lamina IVC alpha the axon terminals of fibres coming from the magnocellular layers of the lateral geniculate nucleus (LGN) make significantly more synapses per bouton than those of fibres arising from the parvocellular layers and terminating in laminae IVA and IVC beta. In all parts of area 17 examined there was a clear difference in the relative proportions of multisynaptic geniculocortical boutons between the alpha and beta divisions of lamina IVC. Calculations have shown that a single cell in the magnocellular laminae of the LGN may make about 6 times as many synaptic contacts within lamina IV of the visual cortex than one in the parvocellular laminae. It has also been estimated that there are at least 500 million geniculocortical boutons, or 1200 million synapses, in lamina IVC alpha and 100 million boutons, 1200 million synapses, in lamina IVC beta for one hemisphere, giving an approximate total number of 1500 million boutons and 2400 million synapses.

Animals↗
PubMed1982

The effect of visual deprivation upon the Meynert cell in the striate cortex of the cat.

The 'solitary cell' of Meynert has been studied during postnatal development in the normal cat and in kittens reared either with unilateral or bilateral eyelid suture, or in the dark. Following dark-rearing there was a marked reduction in the frequency with which Meynert cells could be distinguished compared with the normal, but the effects of eyelid suture were mild. These observations were confirmed in a semi-quantitative study and they indicate that this distinct morphological class of neurone in the striate cortex of the cat may be affected by abnormal visual experience during the critical period.

Animals↗
PubMed1981

The number and distribution of Meynert cells in area 17 of the macaque monkey.

A study has been made of the number and distribution of the Meynert cells in area 17 of the visual cortex in the macaque monkey. There are between 30 000 and 40 000 Meynert cells in one hemisphere and these are randomly distributed with an average uniform area density of about 25 cells per square millimetre. The area density of Meynert cells is similar in the representation of the fovea and the perifoveal cortex. These findings are discussed in relation to the basic uniformity of the functional architecture of the visual cortex.

Animals↗