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Biomedical subjects

D H Brown

Publications and source records attributed to D H Brown.

At least 19 recordsLinked to original sources
PubMed2003

Reconstructive options in the treatment of osteoradionecrosis of the craniomaxillofacial skeleton.

Osteoradionecrosis (ORN) of the craniomaxillofacial skeleton is a serious and debilitating complication that can occur following radiation therapy in the head and neck. Patients require effective treatment, which eradicates diseased tissue and restores function with minimal additional morbidity in a single stage, a requirement fulfilled in many cases by free tissue transfer. In a 6-year period from 1994 to 1999, 21 patients with ORN were treated by wide resection and free-flap reconstruction. The median interval between radiation therapy and ORN was 4 years (range: 1-33 years). The median radiation dose was 6000cGy. The affected areas were the mandible (15 patients), the temporal bone (three patients), the maxilla (one patient), the cervical vertebrae (one patient) and the frontal bone (one patient). Clinical symptoms included pain, ulceration, a persistent draining fistula, exposure of bone or hardware, and pathological fracture or non-union of bone. Six patients had had previous unsuccessful attempts at conservative surgical resection. Ten patients had preoperative hyperbaric oxygen (HBO) therapy. A number of different flaps were used for reconstruction in these patients. These included free fibula flaps (13 patients), iliac crest flaps (two patients), scapula flaps (three patients) and rectus abdominis flaps (three patients). All patients achieved relief from their presenting symptoms and primary bone or wound healing. One flap (4.8%) was lost. This was successfully reconstructed in a subsequent procedure. There were three flap re-explorations, two for arterial thrombosis and one for venous thrombosis. Conservative measures, such as limited debridement and HBO therapy, may be effective in preventing the progression of ORN. However, they fail to eradicate established ORN, which requires radical surgical resection followed by functional reconstruction with well-vascularised tissue.

Aged↗
PubMed2000

Interferons and bladder cancer.

With the introduction of BCG, intravesical instillation of immunotherapeutic agents has become a mainstay of therapy in the treatment of superficial bladder cancer. Interferon is capable of inducing a non-specific cellular and humoral immune response towards tumor cells. It has shown promise in reducing the recurrence and progression rates of superficial bladder cancer. In contrast to BCG, intravesical interferon is associated with minimal side effects and a very low dropout rate. Current research has focused on the use of interferon in combination with immunotherapeutic and cytotoxic drugs.

Administration, Intravesical↗
PubMed2000

The versatile contact Nd:YAG laser in head and neck surgery: an in vivo and clinical analysis.

OBJECTIVE: Lasers have been used in otolaryngology as a surgical instrument for more than 25 years, and the CO2 laser has emerged as the most widely employed surgical laser in use today. However, recent technological advances have made the Nd:YAG laser a challenger as an effective photothermal surgical tool. STUDY DESIGN AND METHODS: This is a two-part study. Tissue injury and healing profiles after application of both the CO2 and Nd:YAG lasers are compared using an in vivo rat tongue model. A prospective clinical review based on the experience of 327 operative cases spanning a 7-year interval using the Nd:YAG laser, highlighting its various applications and associated complications, is detailed. RESULTS: Comparable tissue and healing effects were noted with both lasers in the in vivo rat tongue model with no statistical differences. The clinical application of the laser showed wide versatility in the head and neck with a complication rate of 3%. CONCLUSION: The Nd:YAG laser has proved equivalent in tissue damage and healing to the CO2 laser. The Nd:YAG laser has proved itself to be an excellent and perhaps superior laser for use in head and neck surgery.

Animals↗
PubMed2000

MR appearances of the locked knee.

This review illustrates the MR appearances of commonly encountered problems that can present as a "locked knee", as well as several unusual causes. Internal derangement of menisci, particularly bucket handle tears, predominate. Loose bodies as a result of trauma/degeneration and lesions such as cysts of the cruciate ligaments and focal pigmented villonodular synovitis are also illustrated. While meniscal tears are the major cause of "locked knee" in clinical practice, interference with normal knee kinematics is non-specific with regard to the diagnosis. Emphasis is therefore given to less frequently seen abnormalities that lead to a mechanical block of knee extension.

Anterior Cruciate Ligament↗
PubMed1999

Improving the use of lichens as biomonitors of atmospheric metal pollution.

The data reported on this study supported the hypothesis that the absence of the lichen Ramalina fastigiata near a copper mine site located on the south of Portugal was related to toxic levels of Cu-dust near the centre of the mine. Lichen biodiversity reflected the impact of the copper-mine dust emissions which were more widespread towards the east, correlated with wind direction and frequency. The chemical analysis of R. fastigiata collected at different distances and in different directions from the mine showed that Cu, K and Mg were derived from the centre of the mine site, confirming thus as the major source of atmospheric dust. Total inhibition of PSII photochemical reactions occurred in R. fastigiata both under field and controlled conditions, when intracellular Cu concentrations exceeded a threshold of approximately 2.0 mumol g-1. No samples of this species were found under field conditions beyond the Cu threshold. Thus, the fluorescence parameter Fv/Fm proved to be a good estimator of the survival capacity of R. fastigiata under field conditions and thus a useful parameter in determining the sensitivity of the lichens (photobiont) to Cu pollution. The intracellular location of Cu allowed an explanation of the physiological changes and the survival of the species in the surroundings of the copper-mine.

Air Pollution↗
PubMed1999

Supraomohyoid neck dissection. Is it diagnostic or therapeutic?

BACKGROUND: The supraomohyoid neck dissection (SOHND) is often performed in patients with cancer of the oral cavity, where there is no clinical or radiologic evidence of regional metastases. When on pathologic examination positive neck nodes are found, however, some consider it a curative operation, whereas others regard it as a staging procedure only. METHODS: We retrospectively reviewed 43 patients with cancer of the oral cavity who had a SOHND during the period from 1991 to 1994. All patients were staged as having N0 disease and had a total of 48 SOHNDs (38 unilateral, 5 bilateral). The follow-up period was at least 2 years. RESULTS: Seven of 48 N0-staged necks showed occult metastasis (15%). Two of these patients received postoperative radiotherapy. One of 7 (14%) patients with pathologic node-positive disease on the SOHND side developed recurrent ipsilateral neck disease during the follow-up period, whereas 4 (10%) recurrences developed in 41 necks that were pathologically staged as N0. Survival was 88% for patients with pathologically N0 necks versus 86% for patients with pathologically N+; disease. CONCLUSION: Supraomohyoid neck dissection is an effective staging procedure; however, in this group of patients, neck recurrence and patient survival after SOHND appear not to be related to pathology N stage. Also, SOHND with or without adjuvant radiotherapy appears to control the neck in the majority of patients, attesting to therapeutic efficacy. A prospective study is needed, however, to see if a "wait and see" policy does not achieve similar long-term outcome.

Head and Neck Neoplasms↗
PubMed1999

The free iliac crest and fibula flaps in vascularized oromandibular reconstruction: comparison and long-term evaluation.

BACKGROUND: A variety of free flaps have been successfully used for mandible reconstruction. This study compared the short- and long-term results of using the free iliac crest and fibula flaps. METHODS: We conducted a retrospective analysis of 117 patients who underwent mandibular reconstruction, 59 patients with iliac crest and 58 with free fibula. Accurate long-term functional assessment was possible in 31 cases in the iliac crest group and in 48 patients with fibular reconstruction. Anterior or combined anterolateral defects formed 72% and 64% in the iliac crest and fibula groups, respectively. The remainder were pure lateral defects. In both series, a skin paddle was included to provide either lining, skin cover, or both in 77% of the cases, whereas in 23% bone only was used. RESULTS: Complications included two perioperative deaths and three flap losses in the iliac crest group and five flap losses in the fibula group. Long-term functional and cosmetic assessment showed no statistically significant differences in oral continence (p > 0.9), speech (p = 0.57), and contour results (p = 0.80) between the two groups. However, oral deglutition was statistically significantly better in the fibula free flap group (p = 0.009). CONCLUSION: Although the fibula free flap is the flap of choice, the iliac crest is an excellent and reliable complementary flap for mandibular reconstruction.

Adult↗
PubMed1999

Comparison of computer-assisted instruction and seminar instruction to acquire psychomotor and cognitive knowledge of epistaxis management.

Epistaxis is a common problem faced by primary care physicians. Typically, first-hand experience with this problem is not obtained in medical school. A computer learning module was developed to address practical management of epistaxis. It was evaluated by use of third-year clerks and compared with an interactive seminar based on the same material. Fifty-eight students doing their required otolaryngology rotations were randomly separated into 3 groups: (1) doing a preinstruction test, (2) using the computer module, and (3) participating in a small-group seminar. All participants were tested with a short written test and a practical test that involved performing anterior nasal pack placement in a model patient. Percentage scores for the 2 groups were compared by use of t tests, and there was no significant difference between the written, practical, or combined scores at a level where P = 0.05. This study shows that basic patient management and a simple procedure can be taught as effectively with a computer module as with a small-group interactive seminar.

Clinical Clerkship↗
PubMed1999

Needs assessment for an undergraduate otolaryngology curriculum.

A needs assessment was conducted to determine what family doctors need to know about otolaryngology. A survey was mailed to a group of community otolaryngologists and family doctors. They were asked to rate the importance of 46 otolaryngologic topics. A true needs assessment was carried out with a small group of family practice residents to examine which needs were perceived to be significantly different in importance between these 2 survey groups. A list of important topics was generated from the survey. There were many statistically significant differences between the survey groups, but only 2, vertigo and epistaxis, appeared to be potentially important. The family practice residents (n = 8) were asked to complete a short-answer test about epistaxis management and then to demonstrate placement of an anterior nasal pack. Despite having already faced this problem in 50% of cases, the residents had average scores of less than 30%, indicating a lack of knowledge in this area.

Clinical Competence↗
PubMed1999

Filamentous growth of Candida albicans in response to physical environmental cues and its regulation by the unique CZF1 gene.

Hyphal growth in the opportunistic fungal pathogen Candida albicans is believed to contribute to the virulence of the organism by promoting penetration of fungal cells into host tissue. In this study, stimulation of hyphal growth by a feature of the physical environment was demonstrated. Specifically, growth of cells embedded within a matrix promoted the formation of hyphae. The CZF1 gene, encoding a putative transcription factor, was shown to be involved in the regulation of hyphal growth under certain conditions, including embedded conditions. Ectopic expression of CZF1 in embedded cells promoted the rapid formation of hyphae. Elimination of CZF1 and CPH1, encoding a homologue of the Saccharomyces cerevisiae Ste12p transcription factor, led to a pronounced defect in filamentous growth of embedded cells. Elimination of CZF1 alone led to a moderate defect in hyphal growth under some conditions, including embedded conditions. Hyphal morphogenesis in response to matrix embedding may occur in the opportunistic pathogen, C. albicans, to promote invasion of fungal cells into host tissue.

Candida albicans↗
PubMed1999

A retrospective comparison of the morbidity and cost of different reconstructive strategies in oral and oropharyngeal carcinoma.

PURPOSE: Evaluate and compare the morbidity and costs of different reconstructive strategies in oral and oropharyngeal carcinoma. STUDY DESIGN: Retrospective cross-sectional. PATIENTS AND METHODS: One hundred twenty-seven consecutive patients treated surgically for oral and oropharyngeal carcinoma between 1990 and 1996 were evaluated. Sixty-three patients had segmental mandibulectomies with 30 plate-soft tissue reconstructions and 33 bone-soft tissue flaps. Sixty-four patients had soft-tissue-only reconstructions. The following outcome parameters were analyzed: operative time, intraoperative blood loss, postoperative admission length, ICU and coronary care unit admission length, surgical interventions for complications, re-admissions, and prolonged (>6 mo) gastrostomy tube feeding, and all costs within the disease-free interval. Means and standard deviations were calculated for continuous parameters. Differences among the three groups were analyzed using one-way analysis of variance. For discontinuous parameters, the chi-square test was applied. RESULTS: Longer operative time (1.8 h) and more blood loss (150 mL) for bone-soft tissue flaps were the only statistically significant findings (P<.05) between the three groups. CONCLUSION: There is no rationale for allowing presumed factors of morbidity or cost select for type of reconstruction in patients with oral and oropharyngeal carcinoma.

Adult↗
PubMed1998

Host resistance to mycobacteria is compromised by activation of the hypothalamic-pituitary-adrenal axis.

Host resistance to the growth of Mycobacterium avium and Mycobacterium tuberculosis is controlled by a gene, termed Nramp1, that maps to chromosome 1 in mice. Activation of the HPA axis or treatment of macrophages from susceptible mice with corticosterone suppresses the expression of Nramp1 mRNA and results in an increased susceptibility to mycobacterial growth. In contrast, neither activation of the HPA axis nor treatment of macrophages from resistant mice with corticosterone results in an alteration in their resistance or suppression of Nramp1 expression. Investigation into the mechanism of the differential response of the macrophages to corticosterone indicated that differences were associated with the stability of the mRNA in macrophages from BCG-resistant mice. Thus, corticosterone induced the accelerated degradation of Nramp1 mRNA as well as mRNA of several other macrophage activation genes in macrophages from BCG-susceptible mice. Treatment of macrophages with corticosterone before the induction of Nramp1 resulted in the accelerated degradation of mRNA in macrophages from both resistant and susceptible mice. The Nramp1 gene product appears to protect the mRNA of macrophage activation genes from degradation induced by corticosterone by an iron-dependent mechanism.

Animals↗
PubMed1998

Internal jugular vein thrombosis following modified neck dissection: implications for head and neck flap reconstruction.

BACKGROUND: The incidence of internal jugular vein thrombosis (IJVT) following a modified neck dissection remains uncertain. The effect of, or consequences following, IJVT upon pedicled and free flap head and neck reconstructions remains unexplored. METHODS: Twenty-nine preserved internal jugular veins in 24 patients undergoing modified neck dissection were available for prospective study. All patients required a pedicled or free flap reconstruction and received a modified, unilateral or bilateral cervical lymphadenectomy. The patency of all jugular veins was determined preoperatively and postoperatively using a combination of computed tomography (CT) scanning, high-resolution ultrasound, and color-flow Doppler (CFD). RESULTS: The IJVT rate was 14%. The presence of a pedicled myocutaneous flap and left-sided jugular dissections may represent risks to the postoperative patency of the internal jugular vein. Preoperative radiotherapy did not appear to impact negatively upon the thrombosis rate. CONCLUSIONS: Thrombosis of the internal jugular vein may result in significant morbidity for the postoperative oncologic patient. An internal jugular-dependent-free-tissue transfer may risk venous compromise of the flap, whereas the use of a pedicled flap may place the jugular at increased risk for thrombosis. Strategies for deep venous system microvascular recipient recruitment in the head and neck are discussed. Wherever possible, we employ two deep venous systems, the internal jugular, and subclavian (via the external jugular) for flap drainage.

Aged↗
PubMed1998

An objective analysis of the impact of lateral rhinotomy and medial maxillectomy on nasal airway function.

OBJECTIVE: The lateral rhinotomy and medial maxillectomy procedure, while known to interrupt nasal valve supports, has not previously been reported to adversely affect nasal airway function. The purpose of this study was to utilize state-of-the-art techniques to objectively analyze the impact of this procedure on nasal airway function. DESIGN: The study design was retrospective and subject controlled. METHODS: The study population was derived from an academic, tertiary-referral, otolaryngology-head and neck surgery department with an estimated catchment population of 4 million people. Subjects included 21 consecutive, long-term postoperative patients who had undergone lateral rhinotomy and medial maxillectomy for inverted papilloma. Objective measures included vestibular cephalometric measurements, airflow rhinomanometry, and acoustic rhinometry. RESULTS: Statistically significant results reveal that although lateral rhinotomy and medial maxillectomy are associated with alar collapse, both overall nasal airflow and valve areas are increased. CONCLUSION: Lateral rhinotomy and medial maxillectomy does not adversely affect nasal airway function. This appears to be the result of concomitant resection of the functionally dominant inferior turbinate. This suggests that lateral rhinotomy performed in conjunction with operations not requiring inferior turbinectomy, such as anterior craniofacial resection, may adversely affect nasal airway function.

Acoustics↗
PubMed1998

Pharyngocutaneous fistulae in laryngectomy patients: the Toronto Hospital experience.

OBJECTIVE: The purpose of this study was to determine the rate of post-laryngectomy pharyngocutaneous fistulae and its association with age, gender, preoperative radiation, TNM staging, patients comorbidity factors, choice of ablation, choice of reconstruction, modality of postoperative feeding, and whether or not a primary tracheoesophageal puncture was performed. DESIGN: Retrospective clinical study. SETTING: The Toronto Hospital/Princess Margaret Hospital, University of Toronto, Toronto, Ontario. METHOD: One hundred and twenty-five consecutive laryngectomy procedures performed between July 1, 1992, and October 1, 1996, were reviewed. RESULTS: There was an overall fistula rate of 22%. No association found was between fistula rates and age, gender, patient comorbidity factors, TNM stage, choice of ablation, choice of reconstruction, modality of postoperative feeding, or whether a primary tracheoesophageal puncture was performed or not. CONCLUSIONS: At this tertiary care head and neck oncology centre, pharyngocutaneous fistulae remain an unpredictable and serious complication with an estimated economic cost of Cdn $400,000 per year.

Adult↗
PubMed1998

The value of a routine bone scan in a metastatic survey.

OBJECTIVE: Currently, there is no uniformly accepted metastatic work-up of the patient with head and neck cancer. Various protocols range from selected laboratory investigations and a chest x-ray to more extensive radiologic screening surveys. Although it is desirable to have as much information available as possible prior to making a decision of operability, one is confined by the cost of extensive investigations. This study was conducted to evaluate the benefit of routine bone scanning preoperatively in these patients. METHOD: A retrospective study looked at a consecutive 172 patients undergoing a bone scan with respect to indication, diagnosis, scan result, and tumour stage. RESULTS: Only three patients had a change in their management based on the bone scan results. CONCLUSIONS: The incidence of bone metastases in the majority of patients with squamous cell carcinoma of the head and neck do not warrant routine bone scans for investigation of metastases.

Bone Neoplasms↗