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Biomedical subjects

W Lawson

Publications and source records attributed to W Lawson.

At least 73 records · Page 4Linked to original sources
PubMed1991

Oromandibular reconstruction using microvascular composite free flaps. Report of 71 cases and a new classification scheme for bony, soft-tissue, and neurologic defects.

We describe 71 cases of oromandibular reconstruction using microvascular composite free flaps. There was an overall flap success rate of 94%, while 97% of the patients in this series had their mandibles reconstructed with free vascularized bone flaps. Fifteen patients were rehabilitated with implant-borne dental prostheses. Primary repair of discontinuity defects of the inferior-alveolar nerve using a variety of nerve grafts was performed in 16 patients. A new classification scheme for composite defects of the oral cavity involving bone, soft tissue, and neurologic defects is proposed and applied in the description of each of the patients in this series.

Adult↗
PubMed1991

The intranasal ethmoidectomy: an experience with 1,077 procedures.

A series of 1,077 intranasal ethmoidectomies (825 with sphenoid sinusotomies) was performed in 600 patients over a 15-year period at The Mount Sinai Medical Center. The technique is a modification of the classical operation originally proposed by Yankauer. The rate of significant complications was 1.1%. A subset of 90 patients underwent 166 procedures and were followed an average of 3.5 years. The patients were analyzed according to whether the disease was focal or diffuse, infectious or polypoid, and whether asthma was present. The surgical success rate was 88% in nonasthmatics, but dropped to 50% in asthmatic patients despite total sphenoethmoidectomy. This underscores the importance of this condition as a biological modifier of surgical prognosis. Accordingly, a system of classification of sinus diseases is proposed based upon disease extent and type and whether asthma is present.

Adult↗
PubMed1991

Ultrastructure of melatonin-responsive cells in the ovine pars tuberalis.

Functional receptors for melatonin have been localized and characterized on the pars tuberalis (PT) of a number of mammalian species, but the cell-type responsive to melatonin is unknown. The ultrastructure of the ovine pars tuberalis has been examined and these findings correlated with the functional response of the gland to melatonin. This study revealed that two secretory cell types predominate in the ovine PT, which differ in the abundance of dense-core granules. The most abundant of the cells are either agranular or very sparsely granulated and represent 90% of the total population, with the remaining 10% being composed of cells with abundant dense-core vesicles. Few follicular cells were observed. This ratio of secretory cell-types persisted in primary culture, with the two types non-separable by Percoll gradient centrifugation. Using forskolin, as a non-specific stimulant of adenylate cyclase, melatonin was shown to inhibit the formation of cyclic AMP by 80-90% in cells both before and after Percoll centrifugation. The results demonstrate that the agranular secretory cells of the ovine pars tuberalis are the melatonin responsive cell-type of this gland.

Animals↗
PubMed1991

Unusual aspects of allergic bronchopulmonary fungal disease: report of two cases due to Curvularia organisms associated with allergic fungal sinusitis.

We report two cases of allergic bronchopulmonary fungal disease (ABPFD) caused by Curvularia sp and associated with allergic fungal sinusitis (AFS). Curvularia lunata was cultured in one case and Curvularia senegalensis was cultured in the other. Based on these cases and a review of the literature, we discuss unusual clinical and pathologic features that can occur in ABPFD. Unusual clinical aspects of ABPFD include associated AFS, absence of asthma, progression to Churg-Strauss angiitis and granulomatosis, concomitant hypersensitivity pneumonitis, and underlying cystic fibrosis. Atypical pathologic features that may occur in ABPFD include follicular bronchiolitis, xanthomatous bronchiolitis, limited tissue invasion, fungus balls, and association with unusual fungi. Prominent follicular bronchiolitis and xanthomatous bronchiolitis were misleading histologic features in one of our cases and led to a delay in recognition of the diagnosis. Both patients presented primarily with AFS; ABPFD was detected subsequently. This suggests that a small subset of patients with AFS may be at risk for ABPFD. The goal of this review is to increase awareness of unusual clinical and pathologic manifestations of ABPFD. It is hoped that this will result in accurate diagnosis and proper therapy, especially for patients who present with atypical features. Unusual fungal species should be considered in patients who have clinical findings compatible with ABPFD but who do not demonstrate immunologic reactivity to Aspergillus sp, especially Aspergillus fumigatus. In addition, ABPFD should be considered in patients with AFS who develop new pulmonary lesions.

Adolescent↗
PubMed1991

Simulated aggressive skull base erosion in response to benign sinonasal disease.

Benign sinonasal masses and slow-growing neoplasms tend to remodel the nasal vault and facial bones, and this is particularly true of nasal polyps and inverted papillomas. However, when such benign masses press against the floor of the anterior cranial fossa and the walls of the sphenoid sinuses, simulated aggressive bone destruction rather than bone remodeling usually occurs. This type of bone destruction implies to the radiologist that a carcinoma may also be present, and this information could dissuade a surgeon from operating with an attempt at cure. In fact, about 90% of the time with inverted papillomas and in virtually all cases of nasal polyposis, no carcinoma is present. The computed tomographic (CT) scans and magnetic resonance images of 14 patients are used to demonstrate these changes. In addition, the CT scans of three patients with malignancies are shown to illustrate the similarity in the bony skull base changes.

Diagnosis, Differential↗
PubMed1991

Radiographic evaluation and diagnosis of the failed frontal osteoplastic flap with fat obliteration.

In the absence of evidence of suppurative disease, clinical assessment of the symptomatic patient after frontal osteoplastic flap with fat obliteration is difficult because the cause of the pain is often neuralgic or from chronic vascular headache. Among 59 patients who have undergone this procedure at our institution since 1979, four required revision surgery. These patients were evaluated by computed tomographic and magnetic resonance scans, and the radiographic findings were compared with those present in 20 asymptomatic subjects. On the basis of the results of this study, we believe we can objectively identify those patients with chronic pain in whom the operation has been unsuccessful. A review of our experience with this procedure is presented along with criteria that enable early diagnosis of recurrent disease in the frontal sinus after osteoplastic sinusotomy.

Adipose Tissue↗
PubMed1991

Aggressive juvenile fibromatosis involving the paranasal sinuses.

Aggressive juvenile fibromatosis is a destructive, locally invasive process, with a propensity for local recurrence after inadequate excision. Although it does not metastasize, uncontrolled growth can eventually lead to death. The role for radiation and chemotherapy is controversial and these modalities are best reserved for advanced unresectable or recurrent lesions. The treatment of choice is en bloc surgical resection with wide margins.

Ethmoid Sinus↗
PubMed1991

The Caldwell-Luc procedure in 1991.

In the pre-antibiotic era, George Caldwell and Guy Luc both designed an operation to remove infected polypoid tissue from the maxillary antrum, as well as to provide drainage and ventilation of the sinus. With the development of antibiotics and the surgical endoscopes, many of the former indications for the Caldwell-Luc procedure have changed. However, the Caldwell-Luc procedure still offers optimal exposure for decompression of Grave's ophthalmopathy, pterygomaxillary space surgery, management of some maxillary trauma, removal of antral foreign bodies, repair of some oral-antral fistulae, management of maxillary osteomyelitis and benign maxillary tumors, and irreversible mucosal disease and endoscopic surgical failures.

Humans↗
PubMed1991

The internal oblique-iliac crest free flap in composite defects of the oral cavity involving bone, skin, and mucosa.

The reconstruction of oromandibular defects following ablative surgery is a challenging undertaking. When the defect involves skin as well as mucosa, the challenge becomes even greater. The internal oblique iliac crest osteomyocutaneous free flap is particularly useful for reconstruction of through-and-through composite defects due to the inclusion of two separate soft-tissue flaps on the same vascular pedicle. We report our experience with this flap in the reconstruction of 10 patients with such defects. The utility, and the limitations of this form of reconstruction are discussed in detail.

Aged↗
PubMed1991

Functional evaluation following microvascular oromandibular reconstruction of the oral cancer patient: a comparative study of reconstructed and nonreconstructed patients.

Over the past decade, the use of free flap transfers in head and neck surgery has led to remarkable advances in the reliability and the ultimate results of oromandibular reconstruction. Stable and retentive dental restorations have been achieved using enosseous implants placed directly into the vascularized bone flaps. However, the functional assessment of patients who underwent primary mandibular reconstruction with these techniques has not been previously reported. A group of 10 reconstructed and 10 nonreconstructed segmental hemimandibulectomy patients were compared using a battery of tests to assess their overall well-being, cosmesis, deglutition, oral competence, speech, length of hospitalization, and dental rehabilitation. In addition, objective measures of the masticatory apparatus (interincisal opening, bite force, chewing performance, and chewing stroke) were used to compare these two groups as well as normal healthy subjects and edentulous patients restored with conventional and implant-borne dentures. The results show a clear advantage for the reconstructed patients in almost all categories. Persistent problems and future directions in oromandibular reconstruction are discussed.

Adult↗
PubMed1991

Effects of reducing the remating interval after parturition on the fertility and plasma concentrations of luteinizing hormone, prolactin, oestradiol-17 beta and progesterone in lactating domestic rabbits.

Primiparous crossbred does were remated on Day 1 (n = 15) or 14 (n = 25) post partum and killed on Day 10 post coitum to assess their fertility. Blood samples were taken during the pre- (0-12 h post coitum) and post- (1-10 days post coitum) ovulatory periods and plasma was assayed for luteinizing hormone (LH), prolactin, oestradiol-17 beta and progesterone. Ovulation response was significantly greater (P less than 0.01) and ovulation rate significantly lower (P less than 0.001) in does mated on Day 1 than in those mated on Day 14 post partum. Does failing to ovulate on Day 14 post partum exhibited no preovulatory LH surge and had significantly lower (P less than 0.05) premating concentrations of oestradiol-17 beta and prolactin than those ovulating at this time. No significant differences in hormone concentrations were observed during the preovulatory period between does ovulating on Days 1 and 14 post partum, with the exception of oestradiol-17 beta. Concentrations of this hormone were significantly lower (P less than 0.01) in does mated on Day 1, at 1 h post coitum. We conclude that (i) fertility was affected by the remating interval after parturition, (ii) ovulation failure was associated with an absence of the preovulatory LH surge and a reduction in premating concentrations of oestradiol-17 beta and prolactin and (iii) the lower ovulation rate in early lactation was apparently caused by a reduction in ovarian competence to respond to the gonadotrophic stimulus.

Animals↗
PubMed1991

Intracellular signalling in the ovine pars tuberalis: an investigation using aluminium fluoride and melatonin.

The effect of aluminium fluoride (AlF4-) has been studied on inositol phosphate accumulation, calcium mobilization, cyclic AMP production and [2-125I]iodomelatonin binding in ovine pars tuberalis cells. These cells have high-affinity receptors for, and respond to, melatonin through inhibition of forskolin-stimulated adenylate cyclase. In the presence of 10 mM LiCl, AlF4- stimulated the net accumulation of inositol monophosphate and inositol bisphosphate. Consistent with these findings, AlF4- increased intracellular calcium; although this response was attenuated in calcium-depleted medium, indicating that the calcium response comprises both intracellular and extracellular components. Melatonin was ineffective on either basal or AlF4(-)-stimulated turnover of inositol phosphates. In concordance with the inositol phosphate response, melatonin had no effect on either the AlF4(-)-stimulated or the basal calcium levels. AlF4- blocked the increase in cyclic AMP stimulation by 1 microM forskolin, being as effective as melatonin, achieving approximately 90% inhibition. AlF4- also attenuated the binding of [2-125I]iodomelatonin to ovine pars tuberalis membranes by 15%. At the concentration used, these results are consistent with the interpretation that AlF4- activates many G protein-mediated responses, and thus imply that the inhibitory pathway for cyclic AMP predominates over the stimulatory arm, whereas there can only be a stimulatory pathway linked to phosphoinositide metabolism in ovine pars tuberalis cells.

Aluminum↗
PubMed1991

Jejunal transplantation for pharyngoesophageal reconstruction.

The reconstruction of circumferential and noncircumferential defects of the pharynx and cervical esophagus remains a challenging problem. A variety of different techniques are presently in use for this reconstruction. Free jejunal autografts were the first tissue to be transferred to the head and neck using microvascular techniques. A review of the literature on free jejunal autografts provides a collective experience that permits evaluation of the success rates and complications of the procedure. The results of this review reveal that this method of reconstruction is highly successful in restoring various ablative defects with an acceptable morbidity.

Animals↗
PubMed1990

Combined median mandibulotomy and Weber-Fergusson maxillectomy.

Monoblock surgical resection in combination with radiotherapy remains the most effective method of treatment for advanced carcinoma of the maxillary sinus. Extension of antral carcinoma into the infratemporal and pterygopalatine fossae decreases the probability of achieving an all-encompassing resection via the classic anterolateral Weber-Fergusson approach because of limited posterior access. Temporal and lateral infratemporal fossa approaches have been described and involve either mobilization of the zygomatic arch or a lateral mandibular osteotomy, respectively. We report the use of a median labiomandibulotomy combined with the Weber-Fergusson approach for lesions extending posteriorly. The labiomandibulotomy with paralingual extension along the floor of the mouth allows rotation of the coronoid process laterally and exposes the infratemporal fossa to its posterior margin. We present two cases in which this approach was used to extirpate lesions that had extended posteriorly. Relevant anatomy, operative technique, potential complications, and limitations, as well as a comparison with other methods of exposure, are discussed.

Adult↗
PubMed1990

Multiple intracranial mucoceles associated with phaeohyphomycosis of the paranasal sinuses.

The purpose of this article is to alert clinicians to a new pathogenic fungus of the paranasal sinuses called Exserohilum rostratum. Exserohilum species are one of the etiologic agents of phaeohyphomycosis, a constellation of entities caused by dematiaceous fungi. This class of fungal sinus infection has emerged only in the past decade; it occurs primarily in immunocompetent individuals and produces a tenacious, progressive pansinusitis. To our knowledge, this study describes the first case of multiple intracranial mucoceles secondary to E rostratum. The diagnostic workup includes computed tomography and magnetic resonance imaging followed by direct microscopic examination of tissue biopsy specimens. A craniotomy followed by a bilateral external ethmoidectomy was necessary for complete extirpation of the infected mucoceles. Aggressive surgical management of this mycotic infection is described.

Adult↗