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Biomedical subjects

A S Miller

Publications and source records attributed to A S Miller.

At least 19 recordsLinked to original sources

Review of neural network applications in medical imaging and signal processing.

The current applications of neural networks to in vivo medical imaging and signal processing are reviewed. As is evident from the literature neural networks have already been used for a wide variety of tasks within medicine. As this trend is expected to continue this review contains a description of recent studies to provide an appreciation of the problems associated with implementing neural networks for medical imaging and signal processing.

Diagnostic Imaging

Survey of tissue diagnostic services in U.S. dental schools - 1990.

Tissue diagnostic services in U.S. dental schools were surveyed to determine activities during 1990. Results were compared with those of similar surveys conducted in 1953, 1958, 1969, 1975, 1980, and 1985. The information gathered from this survey reveals a progressive growth and development of tissue diagnostic services. This is seen not only in the increased numbers of biopsy accessions, which increased by 37% since the last survey, but is also reflected in the diversity of services now offered by oral pathologists.

Biopsy

Neural networks for electrical impedance tomography image characterisation.

The Southampton electrical impedance tomography (EIT) system used a Sheffield data acquisition unit and a PC based 'Harlequin' transputer card to reconstruct and display images of the distribution of internal conductivity within the thorax. The system produces real-time images relating to both cardiac and pulmonary function. As a first step towards diagnosis using these images neural nets have been applied to the identification of regions of interest in the EIT images for which some activity with time, such as ventricular ejection, is sought. This paper addresses the use of a back-projection network to identify characteristic regions within the images. The network facilitates the production of automated real-time activity plots by defining their effective extent in the images of specific organs. The application is novel within the medical imaging field as the aim is to use neural networks for real-time image analysis.

Electric Conductivity

Amyloidosis of the oral cavity: report of five cases.

Five cases of amyloidosis involving structures in the oral cavity are reported. Three cases appeared to be secondary systemic amyloidosis, one case was the systemic form associated with multiple myeloma, and one case appeared to represent nodular or localized amyloidosis. All cases appeared in persons over 63 years of age, and the most common area of involvement was the tongue. The nature of so-called amyloid deposits in certain odontogenic tumors is discussed in light of recent knowledge of amelogenins and enamelins.

Aged

Effect of enamel microabrasion compound on human gingiva: report of a case.

A new material to be used in the procedure of enamel microabrasion has been recently introduced. Because the compound contains hydrochloric acid, the manufacturer recommends many safety precautions, especially use of the rubber dam. This case report documents the effect of the enamel microabrasion compound on the gingiva of one human subject and verifies the need for careful handling of the material.

Adult

The relationship between gastrin cells and bombesin-like immunoreactive nerve fibres in the gastric antral mucosa of guinea-pig, rat, dog and man.

The relationship between bombesin-like immunoreactive (bombesin-LI) nerve fibres and gastrin-LI G-cells was examined in gastric antral mucosa from guinea-pig, rat, dog and man using a double-labelling fluorescence immunohistochemical technique. The greatest density of bombesin-LI nerve fibres was found within the basal mucosa in all species and the density of innervation decreased towards the luminal surface. Most G-cells were in a band occupying approximately the middle third of the mucosa. The proportion of G-cells found within a distance of 2 microns from bombesin-LI nerve fibres was low in all species (6% in the guinea-pig, 22% in the rat, 14% in the dog, and 9% in the human). It is proposed that the neuropeptide released from bombesin-LI antral mucosal nerve fibres traverses distances of greater than several microns to reach the target G-cells. This may be achieved by passage through the mucosal microcirculation.

Adult

Survey of tissue-diagnostic services in United States dental schools--1985.

Tissue-diagnostic services in United States dental schools were surveyed to determine activities during 1985. Results were compared with those of similar surveys conducted in 1953, 1958, 1969, 1975, and 1980. A continuing increase in the number of specimens processed has occurred, and there has been a parallel increase in the number of malignant specimens noted. The percentage of malignant specimens in relation to total specimens processed has not changed significantly.

Biopsy

Contamination of perfused donor kidneys by starch from surgical gloves.

Starch induces a variety of inflammatory reactions in humans and may contaminate surgical procedures from surgical gloves. Using polarized microscopy and electron microscopy, the authors observed starch particles in renal perfusate and in glomeruli of perfused donor kidneys. Group 1 consisted of 10 unusable kidneys handled with standard concern of glove sterility. Eight other kidneys (Group 2) were perfused with particular attention toward avoidance of starch contamination. The gloves were rinsed five times, and the cuffs were not dipped into the perfusate. Two kidneys (Group 3), deemed unsuitable for transplantation, were perfused for 24 hours with perfusate swished with unwashed sterile gloves. Group 4 consisted of five transplant biopsies performed within one week after transplantation. Perfusates alone were also circulated through the Waters Perfusion Machine continuously for 24, 72, and 188 hours with and without the use of gloves. The number of birefringent crosses were counted in each of 25 glomeruli per specimen. Group 1 displayed a mean of 1.8 birefringent crosses per glomerulus; Group 2, 0; Group 3, 5.3; and Group 4, 4.4. Groups 1 and 3 also exhibited birefringent crosses in peripheral renal vessels. Perfusate alone, handled without gloves, showed no birefringent crosses; by contrast, perfusate handled with gloves showed numerous birefringent crosses. The authors conclude that starch from surgical gloves can enter the perfusate and lodge in glomeruli and other sites of donor kidneys. Rinsing gloves five times and avoiding contact of the perfusate with the glove cuff effectively eliminates the contamination.

Birefringence

Inverted follicular keratosis.

Inverted follicular keratosis, a benign tumor of the skin believed to arise from the infundibular portion of the hair follicle that can involve perioral skin, has a unique histologic picture. It can be confused with forms of skin cancer; with knowledge of this entity, oral and maxillofacial surgeons may be able to avoid unnecessary surgery. The clinical and microscopic findings of 12 cases of inverted follicular keratosis are reported.

Adult

Craniocervical chordomas.

In a 20 year period seven cases of craniocervical chordoma were seen and treated. Since it is not possible to completely resect these lesions, the aim of treatment has been to debulk the tumor as much as feasible and employ postoperative irridation. Palliation is the most that can be hoped for, and minimal success in delaying the natural history of the tumor has been achieved. Surgery for relief of symptoms secondary to bulky recurrence is indicated for palliation, as is a repeat course of x-ray therapy. Isolated cases of long-term useful survival have followed doses in the range of 10,000 rads or more [19,20]. This therapy is usually given in smaller increments of an initial dose when there is evidence of recurrent tumor or pain [2]. However, whenever the dosage to the spinal cord or the base of the brain exceeds 4,000 rads, there is a concern about possible permanent radiation damage. These patients are difficult to care for late in the course of their disease when multiple cranial nerve paralysis, long tract signs, and intractable pain become progressively severe. Chordomas usually remain localized; however, about 10% metastasize distally. One case is presented of a large retropharyngeal mass with destruction of the second cervical vertebra that recurred locally in 3 months despite usual treatment; distal bony metastases were found 3 years after initial treatment. The histology of the lesion, its recurrence, and distal bony metastases were essentially indistinguishable from the other lesions that remained localized. Short periods of palliation from severe local pain and exquisite tenderness have been achieved by local resection of the involved bones.

Adult

Neurofibroma and schwannoma of the oral cavity. A clinical and ultrastructural study.

The clinical parameters of fifty-five cases accessioned as neurofibroma and schwannoma of the oral cavity were reviewed. An electron microscope study was performed on several cases. The component cells of neurofibroma were spindle shaped, with bundles of collagen fibrils between cells. Junctional complexes were observed between adjacent cells. Component cells of the schwannoma showed numerous convoluted cytoplasmic processes. Reduplication of basal lamina was frequently observed and formed the material in the hyalinized area of Verocay bodies.

Adolescent