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Biomedical subjects

D J Howard

Publications and source records attributed to D J Howard.

At least 37 records · Page 2Linked to original sources
PubMed1998

Craniofacial resection for tumors of the nasal cavity and paranasal sinuses--a 17-year experience.

BACKGROUND: The rarity of sinonasal tumors has precluded long-term follow-up of large series of craniofacial resections until now. METHODS: A series of 209 patients suffering from a wide range of histologies who had undergone craniofacial resection for sinonasal neoplasia with up to 17 years' follow-up were analyzed. RESULTS: An overall actuarial survival of 51% at 5 years and 41% at 10 years was found for the cohort as a whole. For malignant tumors, the 5-year actuarial survival was 44%, falling to 32% at 10 years. For benign pathology, the actuarial survival was 75% at both 5 and 10 years. Statistical analysis identified three factors which significantly affect outcome and survival: malignant histology, brain involvement, and orbital involvement. Few complications are associated with the surgery, with the mean post-operative stay being 16 days. CONCLUSIONS: The improved survival and minimal morbidity and mortality associated with craniofacial resection make it the optimum approach to sinonasal tumors.

Actuarial Analysis↗
PubMed1998

Environmental tobacco smoke in the workplace induces oxidative stress in employees, including increased production of 8-hydroxy-2'-deoxyguanosine.

Environmental tobacco smoke (ETS) is a pervasive contaminant in the workplace. Our objective was to determine the oxidative stress effects of ETS on employees who are exposed. The results provide information that is useful to the resolution of risk assessment questions associated with ETS. We analyzed two blood draws from volunteers in our control and exposed groups. The level of exposure to ETS was determined through plasma cotinine measurements, which showed a 65% increase from the control group to the exposed group. Exposure to ETS resulted in a statistically significant increase of 63% of the oxidative DNA mutagen 8-hydroxy-2'-deoxyguanosine in the blood of exposed subjects. This oxidative DNA damage has been linked to an increased risk of developing several degenerative chronic diseases, including coronary heart disease and cancer. The exposed subjects also had increased levels of superoxide dismutase, catalase, glutathione peroxidase (GPOX), and glutathione reductase. However, these increases were only statistically significant in catalase and GPOX. Catalase levels were 13% higher in the exposed group, and GPOX levels were 37% higher in exposed volunteers. The biochemical evidence suggests that exposure to ETS causes oxidative stress, resulting in DNA damage that may increase the risk of certain diseases.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed1998

Oxidative stress induced by environmental tobacco smoke in the workplace is mitigated by antioxidant supplementation.

Environmental tobacco smoke (ETS) is a pervasive contaminant in the workplace. Previous studies by this laboratory have shown that exposure to workplace ETS results in increased oxidative stress and damage, as measured by increased levels of the antioxidant enzymes superoxide dismutase, catalase, glutathione reductase, and glutathione peroxidase. 8-Hydroxy-2-deoxyguanosine, a marker of oxidative DNA damage, was also 63% greater in the exposed group compared with controls. Subjects in the previous study who reported workplace exposure to ETS were given a 60-day supply of an over-the-counter antioxidant formulation consisting of 3000 microg of beta-carotene, 60 mg of vitamin C, 30 I.U. of alpha-tocopherol, 40 mg of zinc, 40 microg of selenium, and 2 mg of copper. After the 60-day supplementation period, blood samples were again drawn, and the results were compared with the presupplementation values. A 62% decrease in 8-hydroxy-2-deoxyguanosine was observed after supplementation. Lipid peroxidation levels were also decreased, as were the antioxidant enzyme activities. The biochemical evidence suggests that exposure to ETS in the workplace increases oxidative stress and that antioxidant supplementation may provide some protection.

Adult↗
PubMed1997

Closure of the nasal cavities in the treatment of refractory hereditary haemorrhagic telangiectasia.

From a cohort of 35 patients with hereditary haemorrhagic telangiectasia (HHT), 12 patients have undergone closure of the one or both nasal cavities during the last three years for refractory epistaxis. All had failed other forms of treatment including hormone therapy, laser coagulation and septodermoplasty. All patients were available for follow-up at six months or longer. In all patients where complete closure was achieved (11 out of 12) bleeding ceased completely from the operated side.

Adult↗
PubMed1997

A retrospective study of the role of the argon laser in the management of epistaxis secondary to hereditary haemorrhagic telangiectasia.

Epistaxis is a common symptom in patients with hereditary haemorrhagic telangiectasia. It may vary in severity from infrequent mild bleeds to regular severe bleeding, the latter requiring multiple blood transfusions. Laser, which can be used to coagulate the telangiectasia without destroying the overlying nasal mucosa, would theoretically seem to be the ideal mode of treatment. In this pilot study, an argon laser has been used on nineteen patients with hereditary haemorrhagic telangiectasia and is shown to be beneficial in patients with mild or moderate epistaxis. Patients with severe epistaxis, or who fail argon laser treatment, are candidates for alternative therapeutic strategies such as a modified Young's procedure.

Adolescent↗
PubMed1997

Management of laryngotracheobronchial sequelae and complications of relapsing polychondritis.

Relapsing polychondritis is a rare multisystem disorder of unknown etiology characterized by recurrent inflammation and degeneration of cartilage and connective tissue. Laryngotracheobronchial complications are the most severe manifestations of the disease and present the most challenging management decisions. We present four cases of relapsing polychondritis with laryngotracheobronchial manifestations that illustrate the clinical features and review the treatment options.

Adult↗
PubMed1996

Enhanced magnetic resonance imaging and subtraction techniques in postoperative evaluation of craniofacial resection for sinonasal malignancy.

The use of magnetic resonance imaging (MRI) enhanced with gadolinium. and diethylenetriamine pentaacetic acid (DTPA) in the preoperative evaluation of sinonasal malignancy is well established and has an accuracy of over 98%. Since 1979, 208 patients have undergone craniofacial resection at London's Institute of Laryngology & Otology, primarily for sinonasal neoplasia affecting the anterior skull base. Thirty-five "high-risk" patients had MRI at follow-up. The MRI scans were assessed before the patients were examined under anesthesia. MRI was assessed before examination under anesthesia and the results compared with histologic findings demonstrating a reasonable degree of positive correlation but one which is inferior to that found preoperatively (80%). An extension of this technique using the subtraction of T1-weighted MRI with Gd-DTPA highlights areas of increased vascularity, which significantly improves the ability to predict recurrence at the skull base and above the surgical repair in the anterior cranial fossa (94%).

Adult↗
PubMed1994

Vocal fold palsy: a re-evaluation of investigations.

With easier access to more sophisticated imaging techniques, the investigation of vocal fold palsy is reassessed. A questionnaire was sent to all ENT surgeons in the UK to establish which imaging techniques are available to ENT departments and which tests are currently requested during the investigation of vocal fold palsy. An extensive literature review established the aetiology of vocal fold palsy and the sensitivity and specificity of radiological investigations. A simple protocol is proposed which would be suitable to implement in the majority of ENT departments in the UK.

Clinical Protocols↗
PubMed1994

Primary tumours of the trachea: analysis of clinical features and treatment results.

Primary tracheal tumours are extremely rare and present with widely variant clinical and histological features. Treatment methods vary considerably, and few studies have sought to provide adequate guidelines. A retrospective analysis was carried out of all patients treated in our unit between 1965 and 1990. Our experience deals almost exclusively with high tracheal tumours involving the adjacent subglottic region. Squamous carcinoma (SCC) and adenoid cystic carcinoma (ACC) were the commonest subtypes, and presented with dyspnoea and hoarseness as the most frequent symptoms. ACCs occurred commonly in young individuals, presented insidiously, and ran a long, and often, unpredictable course. Endoscopic evaluation revealed the majority of the lesions to be bulky and obstructive in nature. Primary surgery with adjuvant radical radiotherapy, when indicated, appeared to provide optimal results. Debulking surgery followed by radiotherapy provided effective and lasting control in two cases of ACC. Other malignant subtypes behaved aggressively and progressed uncontrolled.

Adolescent↗
PubMed1994

Mesenchymal chondrosarcoma of the maxilla.

We report, to our knowledge, the 10th recorded case of mesenchymal chondrosarcoma (MC) occurring in the maxilla. Our case is the youngest person reported with a tumour in this location. The prognosis for cure is poor with a high incidence of local recurrence as well as metastases. Treatment is based on radical surgery. Radiotherapy and chemotherapy have a adjuvant role but additional experience with this tumour is required to define the most efficacious treatment.

Adolescent↗
PubMed1994

Question effects on question generation and the mediation of attitude change.

80 undergraduates were exposed to arguments advocating supplemental vitamin use. Ending arguments with rhetorical questions (when compared with statements) resulted in more favorable attitudes towards vitamin use and a more favorable profile of questions generated about the message topic. The question profile, principally reflecting uncertainty concerning personal nutrition, mediated the attitudinal effect.

Adult↗
PubMed1993

Laryngeal imaging by computerized tomography and magnetic resonance following radiation therapy: a need for caution.

For patients with laryngeal tumours, the use of computerized tomography (CT) or magnetic resonance imaging (MR) may facilitate accurate staging by the demonstration of cartilage invasion or tumour extension to areas such as the pre-epiglottic space. The role of imaging in the follow-up of patients after radiotherapy, however, has not been examined. A prospective study of 18 patients undergoing laryngectomy was performed. The results of pre-operative CT and MR imaging were correlated with the pathological findings from whole organ axial sections of the laryngeal specimens. In five patients (28 per cent) both CT and MR images were significantly impaired by movement artefact. In the eight patients without previous radiotherapy, seven had adequate quality imaging and both CT and MR accurately demonstrated the site, size and extent of laryngeal tumour. In eight of the ten patients following radiation therapy the presence of tumour was correctly identified, however there was a poor correlation between the imaging and pathological findings. Two patients had radionecrosis alone. Neither CT nor MR imaging could differentiate between radionecrosis and recurrent tumour.

Diagnosis, Differential↗
PubMed1993

Ewing's sarcoma of the nose.

Ewing's sarcoma is a bone tumor that rarely arises in the head and neck region. Head and neck tumors account for only 2% to 3% of all Ewing's sarcomas. There is an extremely rare subgroup of Ewing's tumors, that are histologically indistinguishable, which are not metastatic and arise in soft tissue rather than bone. Two Ewing's sarcomas of the nose are described. One case is the first reported nasal Ewing's soft tissue sarcoma. The other case is the more traditional type involving bone of the nose and extending into ethmoid sinuses and intracranially.

Adolescent↗
PubMed1992

Quality of life of patients treated surgically for head and neck cancer.

The quality of survival of 48 patients treated surgically for head and neck cancer was assessed using a problem-orientated self-administered questionnaire. The questionnaire was based on the European Organization for Research into the Treatment of Cancer (EORTC) core questionnaire to which a specific head and neck module was added. The following domains were studied: pain, fatigue, physical symptoms (gastrointestinal and 'other'), functional activity, psychological symptoms, overall physical condition and overall quality of life. For the analysis, five groups of patients were considered: laryngectomy (n = 15), pharyngolaryngoesophagectomy (n = 5), craniofacial procedure (n = 11), 'other operations' (n = 9) and patients with disease recurrence (n = 8). Each group identified different problem areas. Laryngectomees and 'other operation' patients reported relatively few problems, whereas patients with disease recurrence described difficulties in all of the domains examined. Symptoms of fatigue were common. Information collected in this way may facilitate improved rehabilitation and thus better quality of survival.

Adult↗
PubMed1992

Percutaneous tracheostomy in a head and neck unit.

A recent innovation in the technique of tracheostomy is now available as a commercial kit. A standard tracheostomy tube is inserted using a guidewire and dilator as in the Seldinger technique. The kit was used in nine cases in a unit with a head and neck oncology interest. Two failures were experienced but no serious or fatal complications. The technique is limited when applied to necks which are not anatomically 'ideal', and hence will have application in head and neck surgery only after careful patient selection.

Adolescent↗
PubMed1992

The midfacial degloving approach to sinonasal disease.

The midfacial degloving approach was first described by Casson et al. in 1974 but despite a number of papers in the American literature advocating its use, it has not gained popularity in Europe. The advantages and application of the technique are presented in 36 patients, ranging from 7-78 years of age. The approach is ideally suited for extensive benign lesions in the nasal cavity, ethmoid and sphenoid sinuses and enables access to the nasopharynx and infratemporal fossa whilst avoiding an external incision. These lesions have included angiofibroma (13 cases), inverted papilloma (five cases), a variety of cysts (three cases) and six miscellaneous cases of benign pathology. Malignant lesions which have not breached the anterior cranial fossa may also be removed, up to and including bilateral maxillectomy (nine cases) and this can be combined with orbital clearance. The approach may be repeated if necessary and is associated with few significant complications though vestibular stenosis, oro-antral fistula, nasolacrimal damage and upward rotation of the nasal tip may occur. Strategies to avoid these problems can be undertaken and long-term cosmetic results are excellent.

Adolescent↗
PubMed1991

Large-area plan-view sample preparation for GaAs-based systems grown by molecular beam epitaxy.

We describe a method for plan-view transmission electron microscopy (TEM) sample preparation that takes advantage of extreme etch-rate selectivity in GaAs and AlAs in HF/H2O solutions. GaAs/InxGa1-xAs/GaAs strained-layer films (x = 0.05, 0.10, 0.19, 0.22) were chemically lifted off using this technique and were mounted on Cu TEM grids such that TEM transparent areas of up to 1 x 2 mm of constant thickness (196.4 nm) could be viewed. This simple, large-area plan-view technique uses only chemical methods and significantly extends the usefulness of TEM for the evaluation of crystal quality in GaAs-based epitaxial systems. The method requires the growth of a release layer of AlAs (10 nm thick) prior to the layered structure of interest.

Microscopy, Electron↗