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Biomedical subjects

W B Stewart

Publications and source records attributed to W B Stewart.

At least 19 recordsLinked to original sources
PubMed1992

Temporoparietal fascial flap for orbital and eyelid reconstruction.

The temporoparietal fascial flap is a recognized technique for the transfer of vascularized tissue in the craniofacial region. The flap has a predictable axial vessel, provides thin vascularized tissue, and can be harvested with minimal donor-site morbidity. The temporoparietal fascial flap is well suited for orbital or eyelid reconstruction because of its proximity to the orbit. The flap is useful for reconstruction of anatomic barriers between the orbit, intracranial cavity, and paranasal sinus spaces. We present four patients in whom the temporoparietal fascial flap was used for orbital reconstruction following extirpative surgery for orbital neoplasm and two patients in whom the flap was used for lower eyelid and malar reconstruction.

Adult↗
PubMed1992

Indomethacin promotes germinal matrix microvessel maturation in the newborn beagle pup.

BACKGROUND AND PURPOSE: Although indomethacin has been demonstrated to prevent germinal matrix and intraventricular hemorrhage in clinical and animal studies, the mechanism of action of this agent to prevent hemorrhage remains unclear. Previous studies have demonstrated both that the microvessels in the germinal matrix of newborn beagle pups undergo basement membrane maturation during the first 4 postnatal days and that indomethacin may promote laminin deposition in tumor cell culture systems. METHODS: We employed the newborn beagle pup model to test the hypothesis that indomethacin may stimulate laminin deposition in germinal matrix microvessels. Newborn pups were randomized to receive either 0.1 mg/kg/dose i.p. indomethacin or an equal volume of saline diluent. Pups received doses of study medication once a day for 1, 2, or 3 days and were studied on postnatal days 1, 2, 3, or 4. Pups were anesthetized and systemically perfused with buffered formalin; the brains were removed and prepared for immunohistochemical study. RESULTS: Sections stained with Bandeiraea lectin demonstrated that there was no difference in germinal matrix vessel density among the postnatal ages studied; similarly, there were no differences in vessel density between saline- and indomethacin-treated animals at any postnatal age. Quantification of germinal matrix stained intensity by confocal microscopy demonstrated significant increases in indomethacin-treated pups for both laminin staining at postnatal days 2 (p = 0.05) and 3 (p = 0.0009) and type V collagen staining at postnatal day 2 (p = 0.011). Although staining for beta 1 integrins increased across postnatal ages, there were no differences between saline- and indomethacin-treated animals. CONCLUSIONS: These data suggest that indomethacin may stimulate basement membrane deposition in the germinal matrix microvessels of newborn beagle pups to prevent germinal matrix and/or intraventricular hemorrhage.

Animals↗
PubMed1992

Three dimensional imaging and computer-designed prostheses in the evaluation and management of orbitocranial deformities.

Three dimensional images reconstructed from two dimensional CT scans allow improved analysis of complex orbitocranial bony deformities. This evaluation may be useful in patients with defects resulting from trauma, tumor, congenital abnormalities, or developmental disorders. Diagnosis, surgical management, and long-term follow-up evaluation may be aided by improved understanding of bony contour and volume analysis. Computer designed prostheses can be fabricated to precisely match bony defects and may be used as an alloplastic implant or as a model to aid intraoperative contouring of an autogenous bone graft. The limitations of three dimensional imaging include artifacts in the reconstructed images, increased radiation exposure, and increased cost. The technology is still evolving and the indications and benefits remain undefined at the present time.

Adolescent↗
PubMed1991

Orbital exenteration. The reconstructive ladder.

Following orbital exenteration, there is a spectrum of immediate and delayed options for orbital reconstruction. Goals of reconstruction after exenteration include detection of recurrent disease, restoration of boundaries between the orbit and surrounding structures, and optimal aesthetics. Local solutions to problems of the exenterated orbit, such as healing by granulation or application of split-thickness skin grafts, are advantageous for detecting recurrent disease. Regional solutions, involving transfer of periorbital tissue into the orbit, may mask recurrent disease and create adjacent deformity; however, these solutions can be used to restore orbital boundaries and shallow the orbital cavity. Distant solutions, such as skin-muscle flaps and free tissue grafts, allow for facial reconstruction in patients with extensive orbital and periorbital defects.

Adipose Tissue↗
PubMed1991

A micro system for rigid bony fixation in orbital surgery.

Plates and screws are effective for rigid internal fixation of bone fractures and osteotomies in the midface, orbit, and cranium. We describe our experience with the Luhr Micro System. This is the newest generation of Luhr Systems and is the smallest system available for rigid internal fixation. The self-tapping screws are 0.8 mm in diameter, with lengths of 2-8 mm. The plates have an extremely flat profile. We have used the Micro System for closure of elective osteotomies following resection of orbital neoplasm, bony orbital reconstruction, and repair of congenital craniofacial deformities. Because the orbital bones have minimal functional stress, the Micro System provides adequate support. The plates are not apparent through the thin periorbital skin. For bony fixation in the periorbital region, the Micro System appears superior to larger systems and to wire or nonabsorbable sutures.

Adult↗
PubMed1991

Beagle pup germinal matrix maturation studies.

Intraventricular hemorrhage, or hemorrhage into the germinal matrix tissues of the developing brain, remains a common problem of preterm infants. The "risk period" for this insult is the first 3-4 postnatal days. We hypothesized that this risk period for hemorrhage is related to rapid perinatal maturation of the germinal matrix vasculature and employed the newborn beagle pup model for the study of this maturation. Newborn beagle pups (n = 30) were anesthetized and systemically perfused with buffered formalin; the brains were removed and prepared for immunohistochemical study. Sections stained with Bandeiraea lectin demonstrated that there was no difference in germinal matrix vessel density between postnatal days 1 and 4. Germinal matrix sections were also stained for antibodies to alpha-smooth muscle actin, collagen IV, collagen V, desmin, factor VIII-related antigen, fibronectin, glial fibrillary acidic protein, laminin, transferrin, and vimentin. Vasculature staining by alpha-smooth muscle actin was not noted until postnatal day 10, and differential staining was detected for antibodies to laminin and collagen V. Quantification of staining intensity by confocal microscopy demonstrated a significant increase in both extracellular matrix components at postnatal day 4 compared with day 1 (p less than 0.05 for both). These basement membrane proteins may add sufficient structural integrity to germinal matrix vessels to prevent capillary rupture and thus intraventricular hemorrhage.

Aging↗
PubMed1987

The spatial organization of olfactory nerve projections.

The spatial organization of olfactory nerve projections was examined in the rat. The pathway was traced by orthograde transport of HRP following nasal lavage and by retrograde transport of HRP following injections into the olfactory bulb. The results indicated that there was a broad relationship between the epithelium and the olfactory bulb. Specific regions of the olfactory bulb received input from a large region of the epithelium. However, there was evidence that olfactory nerve terminations were not uniformly dense across their terminal fields. The results suggest that there may be finer sorting of olfactory nerves based on functional specificity.

Animals↗
PubMed1985

Labelling of olfactory bulb glomeruli following horseradish peroxidase lavage of the nasal cavity.

The transport of horseradish peroxidase (HRP) from the nasal cavity to the olfactory bulb was examined in rat. HRP was present primarily in the olfactory nerve and glomerular layer. In some animals the glomeruli were densely filled with product while in others there was considerable interglomerular variation in density. Examination of the decalcified noses revealed a restricted distribution of HRP in those rats with partially labelled olfactory bulbs. The presence of small groups of densely labelled glomeruli was also noted using the 2-deoxyglucose method to examine odor-induced metabolic activity.

Animals↗
PubMed1979

Functional organization of rat olfactory bulb analysed by the 2-deoxyglucose method.

The spatial patterns of activity elicited in the rat olfactory bulb under different odor conditions have been analysed using the 2-deoxyglucose (2DG) technique. Rats were injected with 14C-2DG, exposed to controlled environments of amyl acetate, camphor, cage air, dimethyl disulfide, and pure air and autoradiographs prepared by the method of Sokoloff. Amyl acetate was associated with regions of glomerular layer densities in the anterolateral and mid- to posteromedial parts of the bulbar circumference, as previously reported. The extents of the densities increased with increasing concentration. Camphor odor was associated with regions of increased density in the anterodorsal and mid- to posteromedial parts of the bulb. Exposure to cage air produced scattered densities in the posteromedial and posterolateral bulb. Exposure to dimethyl disulfide gave variable results. Pure air was associated with a minimal number of small dense foci. The results with amyl acetate, camphor and cage air suggest that patterns for different odors are distinguishably different but overlapping. The regions of activity are greatest in extent and density with the highest odor concentrations. These define the regions within which more restricted and isolated foci appear at lower concentrations. The results thus provide evidence for the specific role of spatial factors in the neural processing of odor quality and odor concentration.

Acetates↗
PubMed1979

Mechanisms of augmented field potential responses in the rat olfactory bulb.

Olfactory bulb field potential and single unit responses to paired pulse stimulation of the lateral olfactory tract were observed in the rat. In agreement with previous reports, surgical levels of barbiturate anesthesia prolonged the period of diminution of the field potential responses to the test pulse relative to the effect seen under light anesthesia. Very deep barbiturate anesthesia (sufficient to depress the EEG) led to decreased responses to the primary pulse but augmented responses to the test pulse. Urethane and ether anesthesia produced augmented test responses without severely depressing the EEG and without producing a period of diminished test responses. Single unit recordings failed to show external plexiform layer units excited at the time of maximal augmentation of the field potential. Simultaneous single unit and field potential recordings showed that prolonged diminution of the field potential response was associated with prolonged suppression of unit responses to the test pulse, while augmented field potential responses were associated with decreased suppression of unit responses to the test pulse. These observations are most easily explained by the assumption of temporal facilitation in the synaptic output of mitral and tufted cells. This facilitation is masked by feedback inhibition under some conditions, particularly under barbiturate anesthesia.

Anesthesia, General↗
PubMed1979

Lacrimal gland and fossa lesions: an approach to diagnosis and management.

Lesions of the fossa of the lacrimal gland present special problems in diagnosis and management. Clinical recognition and differentiation of benign mixed cell lacrimal gland tumors from other inflammatory and neoplastic lesions of the lacrimal gland fossa are feasible and should provide the basis for the approach to proper management. Lesions conforming to the clinical picture of benign mixed cell lacrimal gland tumors need not undergo incisional biopsy, but require en bloc excision with adjacent tissues through a lateral orbitotomy to ensure complete excision and to prevent late recurrence. Incisional biopsy is indicated and should not be delayed in suspected infectious and noninfectious inflammatory lesions that have not responded rapidly to medical therapy, and in other lesions suspected of being neoplastic and not amenable to total local excision. An expedient approach to these lesions is essential if the prognosis of epithelial lacrimal gland neoplasms is to be improved.

Adult↗
PubMed1979

Clinical presentation and management of lacrimal gland tumours.

This paper presents the clinical and pathological findings in 40 consecutive patients seen with primary tumours arising from the lacrimal gland. Twenty patients had a benign mixed-cell tumour. They presented in a recognisable clinical manner with a painless mass in the region of the lacrimal gland which slowly enlarged over a period of at least 1 year before consultation. Twenty patients had a carcinoma of the lacrimal gland. They had a short history and experienced pain. On clinical grounds they could not be distinguished from inflammatory lesions in the region of the lacrimal gland. The method of treating these 2 groups of patients is described and methods of dealing logically with their problems are suggested.

Adult↗
PubMed1979

Vascular ectasias of the colon.

Vascular ectasias are an acquired type of arteriovenous malformation distinct from neoplastic and congenital lesions. They can be the source of occult, recurrent or massive colonic bleeding usually in elderly patients but, occasionally, in younger adults. The vascular lesions are usually small but can be quite diffuse. The majority occurs in the right colon, but in our group of patients, a substantial number occurred distal to the hepatic flexure. The diagnosis can be made preoperatively, with colonoscopy but, more consistently, with arteriography. Therefore, arteriography should be performed in any patient with bleeding of the colon before surgical intervention. We recommend resection of the involved segment of the intestine as the treatment of choice.

Angiography↗
PubMed1979

Early medicine and surgery in New Brunswick.

The author discusses some of the major events in medicine and surgery in New Brunswick prior to 1900. The influences of Indian medicine, of early French and Acadian surgeons, of the British colonial surgeons at the siege of Fort Beausejour, of the pre-Loyalist and Loyalist surgeons all led up to the building of marine hospitals and quarantine stations. The introduction of anesthesia with ether and chloroform hastened progress towards"modern surgery" which was carried out in the many general hospitals that were built following the opening, in 1865, of New Brunswick's first general hospital, the General Public Hospital (now the saint John General Hospital).

England↗
PubMed1978

Fibrous histiocytoma metastatic to the orbit.

The term fibrous histiocytoma encompasses a heterogenous group of tumors believed to have a common origin in the histiocyte. These tumors demonstrate a wide histopathologic spectrum ranging from a predominantly cellular to a predominantly fibrous pattern. No clinical or histological criteria have been identified that can predict malignant behavior. Although generally characterized by local recurrence, a metastatic potential does exist. Fibrous histiocytoma of the thigh metastasized to the orbit.

Diagnosis, Differential↗