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L T Ellison

Publications and source records attributed to L T Ellison.

At least 19 recordsLinked to original sources
PubMed1994

Variogram methods for the analysis of bony trabecular shadows in plain radiographs.

Conventionally, trabecular morphology is described from thin sections on the basis of visual inspection and basic biometric parameters such as mean trabecular plate thickness, bone density, etc. In the clinical situation non-invasive studies of mineralised tissues may be undertaken using densitometric measurements. A little-explored non-invasive alternative is to study the organisation of shadows of trabeculae in plain radiographs. In radiographic images cancellous bone appears as a texture made up of the superimposed shadows of trabeculae from many planes. In this paper some early attempts to adapt modern image processing techniques to the analysis of trabecular architecture are reviewed. A new statistical technique based on variograms is applied to the investigation of anisotropy in trabecular radiographs and to changes in anisotropy with age. The results of regression analyses of variograms indicate that they can clearly demonstrate age-related changes in trabecular architecture and discriminate between the pattern of ageing in males and females. This approach shows promise as a useful research and investigative tool in a variety of contexts.

Absorptiometry, Photon↗
PubMed1977

The uptake of horseradish peroxidase by cortical synapses in rat brain. An in vivo study.

Horseradish peroxidase (HRP) was introduced directly into the cerebral cortex of adult rats, which were allowed to survive for 60 min before perfusion fixation. After the tissue had been incubated to demonstrate HRP at the LM and EM levels, blocks of cortical tissue were taken at varying distances from the injection site. These eight blocks of tissue constituted a time sequence for HRP diffusion. Qualitative examination of the presynaptic terminals showed that the most commonly encountered profiles are the plain synaptic vesicles, many of which accumulate tracer. In some terminals labelled vesicles are "lined-up" in tubular fashion. Other profiles commonly labelled are coated vesicles, tubular and vacuolar cisternae, and plain and coated pinocytotic vesicles. Quantitative analyses based on the number of terminals containing labelled profiles demonstrate an early rise in the rate of labelling of both plain synaptic vesicles and coated vesicles, after which synaptic vesicle labelling rises slowly towards a plateau. By contrast, there is a late parallel increase in the rate of labelling of coated vesicles and cisternae. A more detailed analysis, based on the actual numbers of labelled and total profiles within each presynaptic terminal, highlight early and late periods of rapid labelling for plain synaptic vesicles, coated vesicles and cisternae. A further aspect of HRP incorporation studied, concerns its uptake into four delineated regions of the presynaptic terminal. Our data indicate that membrane uptake into the presynaptic terminal is accomplished mainly via coated vesicles, although plain synaptic vesicles may also be involved. Coated vesicles, in turn, appear to give rise directly to plain synaptic vesicles, with some coalescing to produce vacuolar cisternae. The latter are involved in a two-way interchange of membrane with tubular cisternae, plain synaptic vesicles and coated vesicles. An additional source of plain synaptic vesicles are the tubular cisternae. Exocytosis of plain synaptic vesicles constitutes the mechanism by which transmitter is released from the presynaptic terminal.

Animals↗
PubMed1976

A critical evaluation of the relationship between the presynaptic network, synaptic vesicles and dense projections in central synapses.

Synapses of the oculomotor nucleus of Echidna have been examined ultrastructurally with the aim of integrating data obtained from osmicated and nonosmicated PTA stained material. Particular emphasis has been laid on the relationship between the synaptic vesicles of the osmicated material and the presynaptic network and vesicular grid of the PTA material. This relationship has been explored qualitatively by examining osmicated material of varying qualities of fixation. Such material contains dense projections in addition to synaptic vesicles, and various vesicular network appearances. A variety of measurement techniques have shown that the PTA network is characterised by reticular strands, spaces, and regular hexagonal units smaller than vesicles, these observations prompting the formulation of a "vesicle-network coincidence" model of the presynaptic terminal. This model has been tested by tracing the profiles of vesicles within the PTA network and comparing their size and shape frequency distributions with those of osmicated synaptic vesicles. The distributions have been found to be essentially similar, suggesting that vesicles can be located within the network, and that the hexagonal network units are formed only in the presence of an underlying vesicular matrix. Additionally, the following points have emerged: 1) the dense projections in the two types of material appear to be quivalent; 2) a loose correlation exists between dense projections and vesicles in osmicated terminals, increase in the area of the dense projections being associated with a decrease in the area of the vesicles; 3) network and dense projection units are similar. In view of the similarity between network and dense projection units, the demonstrated vesicular basis of the network raises the question of whether dense projections are entirely independent structures, or whether they depend in part for their existence on the nearby presence of synaptic vesicles.

Animals↗
PubMed1976

Soft-palate pigmentation in lung disease, including cancer.

A study of patients in whom soft-palate pigmentation appeared to be associated with pulmonary disease has been reported. A significant number of these patients had diagnosed or suspected bronchogenic carcinoma. The possibility that this oral finding may be predictive of the presence of lung cancer, or of a high degree of probability of future development of lung cancer, indicates a need for additional investigation. At this point the evidence strongly suggests that when soft-palate pigmentation is seen in a patient with lung disease, cancer should be suspected until it is definitely ruled out. The paucity of patients in whom this sign is seen suggests the need for study by other investigators. ACTH levels should be evaluated, as should plasma zinc values, which have been demonstrated to decrease in lung cancer as well as other diseases. Following the patients prospectively certainly is indicated. In conjunction with the Department of Laboratory Medicine, limited initial additional investigations have been made of the carcinoembryonic antigen (CEA) levels on three of the outpatients reported. These assays used the hemagglutination-inhibition technique and are limited to investigational use by the Food and Drug Administration. In this laboratory the normal CEA level is 5.2 +/- 1.6 ng./ml. Results in two patients with known chronic obstructive pulmonary disease were 5.5 and 5.6 ng./ml. The third patient with soft-palate pigmentation and an undiagnosed pulmonary problem had a CEA level of 10.2 ng./ml. She also had clubbing of the fingers. The senior author would be particularly interested in establishing a registry of similar cases observed by others.

Female↗