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Biomedical subjects

D Callender

Publications and source records attributed to D Callender.

At least 19 recordsLinked to original sources
PubMed2001

Transmandibular, circumglossal, retropharyngeal approach for chordomas of the clivus and upper cervical spine. Technical note.

Extensive clival tumors that involve both the midline and lateral skull base compartments, or those that extend inferiorly to the anterior cervical spine, are difficult to expose in a wide fashion using any of the transmaxillary, transoral, or transcervical routes. In the transmandibular, circumglossal, retropharyngeal (TCR) approach wide access of this region can be obtained, thus allowing for a more complete resection of tumor and infiltrated bone. It also provides for an improved ability to perform dural reconstruction, should it be necessary. Over the past 4 years four patients with extensive clival chordomas underwent resection via the TCR approach. Gross-total resection was achieved in two patients, a greater than 98% resection in one patient, and a greater than 95% resection in the fourth patient. The surgical technique, all approach-related complications and morbidity, and patient outcome are discussed. If an expanded exposure of the clivus is necessary, the TCR approach is a good choice as well as a useful surgical technique to have available.

Adult↗
PubMed2000

The impact of clinical pathways on the practice of head and neck oncologic surgery: the University of Texas M. D. Anderson Cancer Center Experience.

OBJECTIVE: To assess the impact of clinical pathways on the practice of head and neck oncologic surgery in an academic center. DESIGN: Cross-sectional study. SETTING: Cancer treatment center. PATIENTS: The study population consisted of 3 groups of patients who underwent unilateral neck dissection and were treated in the Department of Head and Neck Surgery of the University of Texas M. D. Anderson Cancer Center, Houston. Additional procedures which may have been performed were direct laryngoscopy, rigid esophagoscopy, and/or dental extractions. Ninety-six patients treated during 1993-1994 prior to the implementation of the clinical pathway (historical control group) were compared with 94 patients treated during 1996-1998, 64 who were not (contemporaneous nonpathway group) and 30 who were managed on the clinical pathway (pathway group). Patients from 1995 were excluded since the pathway was in the planning stages then. MAIN OUTCOME MEASURES: Median length of stay; median total costs of care. RESULTS: The median length of hospital stay of the historical control, contemporaneous nonpathway, and pathway groups decreased from 4.0 to 2.0 days (P<.001). The total median costs of care were less in the pathway group as compared with the historical control group ($6,227 and $8,459, respectively, P<.001) and also less in the contemporaneous nonpathway group compared with the historical control group (S6885 and $8,459, respectively, P<.001). Mean and median length of hospital stay and costs were lower in the pathway group as compared with the nonpathway group but not significantly (P = .11 and P = .07, respectively) The contemporaneous nonpathway and pathway groups did not differ in complications or readmissions. CONCLUSIONS: Development and implementation of this clinical pathway played a statistically significant role in decreasing length of hospital stay and total costs of care associated with neck dissection between nonpathway and pathway patients. Thus, a more cost-effective practice environment has resulted for all of our patients.

Academic Medical Centers↗
PubMed2000

Esophageal candidiasis in pediatric acquired immunodeficiency syndrome: clinical manifestations and risk factors.

BACKGROUND: Little is known about the epidemiology and clinical features of esophageal candidiasis (EC) in pediatric AIDS. We therefore investigated the clinical presentation and risk factors of EC in a large prospectively monitored population of HIV-infected children at the National Cancer Institute. PATIENTS AND METHODS: We reviewed the records of all HIV-infected children (N = 448) followed between 1987 and 1995 for a history of esophageal candidiasis to characterize the epidemiology, clinical features, therapeutic interventions and outcome of esophageal candidiasis. To understand further the risk factors for EC in pediatric AIDS, we then performed a matched case-control analysis of 25 patients for whom control cases were available. RESULTS: There were 51 episodes of EC documented in 36 patients with 23 male and 13 female patients (0.2 to 17 years; median CD4, count 11/microl), representing a frequency of EC of 8.0%. Concurrent oropharyngeal candidiasis (OPC) was the most common clinical presentation of EC (94%); other signs and symptoms included odynophagia (80%), retrosternal pain (57%), fever (29%), nausea/vomiting (24%), drooling (12%), dehydration (12%), hoarseness (6%) and upper gastrointestinal bleeding (6%). The causative organism documented in 36 episodes (18 from OPC, 17 from endoscopic biopsy and 1 from autopsy) was Candida albicans in all cases. Patients received treatment for EC with amphotericin B (63%), fluconazole (29%), ketoconazole (4%) or itraconazole (1%). A clinical response was documented in all 45 evaluable episodes. In 6 other cases, EC was a final event without contributing to the cause of death. By a conditional logistic regression model for matched data, the best predictor of EC was the presence of prior OPC (P<0.0001), followed by CD4 count and CD4 percentage (P = 0.0002) and use of antibacterial antibiotics (P = 0.0013). The risks associated with low CD4 count were independent of that of prior OPC. CONCLUSION: EC in pediatric AIDS is a debilitating infection, which develops in the setting of prior OPC, low CD4 counts and previous antibiotics.

AIDS-Related Opportunistic Infections↗
PubMed2000

Molecular genetic alterations in carcinoma ex-pleomorphic adenoma: a putative progression model?

To determine the genetic changes associated with the development of carcinoma ex-pleomorphic adenoma (Ca Ex-PA), we analyzed 15 microsatellite loci at chromosome arms 8q, 12q, and 17p on DNA from 26 neoplasms (including 8 microdissected benign and malignant components), and 13 pleomorphic adenomas for comparison. Pleomorphic adenomas and the adenoma component of Ca Ex-PAs showed a higher incidence of loss of heterozygosity (LOH) at chromosome arms 8q (52%) and 12q (28%) than at 17p (14%) loci. In the carcinoma component, the combined LOH at chromosome arm 8q, 12q, and 17p regions was 69%, 50%, and 69%, respectively; within these chromosomal regions, 8q11.23-q12 (42%), 12q23-qter (39%), 17p13 (41%), and 17p11 (45%) loci manifested the highest incidence of LOH. Eight carcinomas (30.7%) showed loss at all three chromosomal arms tested. Of the eight microdissected Ca Ex-PAs analyzed, four adenoma and corresponding carcinoma components (50%) had the same LOH at 12q loci and additional LOH at 17p loci only in carcinomas. Chromosome arm 17p alterations correlated significantly with high disease stage and an increased proliferative rate in these tumors. Our results indicate that alterations at regions on chromosome arms 8q and/or 12q may constitute early events associated with pleomorphic adenomas; that LOH at 12q loci may identify a subset of adenoma with potential progression to carcinoma; that acquisition of additional alterations at chromosome arm 17p loci might represent an event preceding malignant transformation and progression; and that 8q, 12q, and 17p regions may harbor tumor suppressor genes involved in the genesis of PA and Ca Ex-PA. Genes Chromosomes Cancer 27:162-168, 2000.

Adenocarcinoma↗
PubMed1998

Genetic alterations in acinic cell carcinoma of the parotid gland determined by microsatellite analysis.

We investigated, for the first time, the genetic alterations at certain chromosomal loci in 25 primary parotid acinic cell carcinomas to define the most frequently altered chromosomal regions and their association with pathologic features and DNA content analysis. Our results showed that 21 (84.0%) of the tumors had alteration in at least one of the loci tested. In general, chromosomal regions at chromosomes 4p, 5q, 6p, and 17p were more frequently altered than those on chromosomes 1p and 1q, 4q, 5p, and 6q. Certain markers at 4p15-16, 6p25-qter, and 17p11 regions showed the highest incidence of LOH, suggesting the presence of tumor suppressor genes associated with the oncogenesis of these tumors. LOH was significantly associated only with tumor grade. No apparent correlation between LOH and other clinicopathologic and DNA content characteristics was identified. Our study broadly defined the chromosomal arms and loci that may be targeted for further localization of the minimally deleted regions involved in the tumorigenesis of these tumors.

Adult↗
PubMed1998

Ethmoid sinus carcinomas: natural history and treatment results.

PURPOSE: This retrospective study was undertaken to assess the clinical features and results of treatment of carcinomas of the ethmoid sinus. MATERIALS AND METHODS: The records of 34 patients with ethmoid sinus carcinomas treated with curative intent at the U.T.M.D. Anderson Cancer Center (UTMDACC) between January 1969 and December 1993 were reviewed. The age of the patients ranged from 28 to 73 years with a median of 57 years. There were 28 Whites, four Hispanics, one Black and one Asian. A simple staging based on anatomical criteria was used to describe the extent of the disease. Six patients had T1, 13 patients had T2 and 15 patients had T3 disease. Twenty-one patients were treated with surgery plus radiation and 13 patients were treated with radiotherapy alone; nine patients received adjuvant chemotherapy. Radiation was given at approximately 2 Gy per fraction to total doses of 50 Gy preoperatively, 52-66 Gy (median 60 Gy) postoperatively and 50-70 Gy (median 63 Gy) when no surgery was performed. RESULTS: The actuarial 5-year overall, disease-free and disease-specific survival rates were 55%, 58% and 63%, respectively. The actuarial 5-year local control rate was 71% for the whole group (74% for surgery plus radiation and 64% for radiation alone). Local recurrence occurred in nine patients, nodal relapse occurred in three patients and distant metastases occurred in four patients. Histologically proven dura mater invasion was associated with a poorer local control rate in patients undergoing surgery and radiation. The simple T-staging system used in this study was a good discriminator for local control. Of nine patients receiving chemotherapy, three had complete responses and four had partial responses; six of the seven responders had undifferentiated carcinoma. Severe complications of therapy occurred in patients treated between 1969 and 1984 and consisted mainly of visual impairment and brain necrosis. CONCLUSIONS: This retrospective review of a large single institutional experience showed that ethmoid sinus carcinomas have a tendency for extensive local invasion but a low propensity for lymphatic and hematogenous spread. Hence, local recurrence was the main cause of cancer-related death. Combined treatment with surgery and postoperative irradiation yielded the highest local control rate. However, radiotherapy alone eradicated two-thirds of primary tumors and, consequently, is a reasonable alternative treatment for patients with medical contraindications to surgery. For patients who underwent surgery and radiotherapy, the presence of histologically proven dura mater invasion was associated with a higher local recurrence rate. Severe radiation complications have been rare with the contemporary radiotherapy technique. Chemotherapy induced excellent responses in undifferentiated carcinoma but its impact on overall disease control is unclear in this small series of patients.

Adult↗
PubMed1998

Compartmental pharmacokinetics and tissue drug distribution of the pradimicin derivative BMS 181184 in rabbits.

The pharmacokinetics of the antifungal pradimicin derivative BMS 181184 in plasma of normal, catheterized rabbits were characterized after single and multiple daily intravenous administrations of dosages of 10, 25, 50, or 150 mg/kg of body weight, and drug levels in tissues were assessed after multiple dosing. Concentrations of BMS 181184 were determined by a validated high-performance liquid chromatography method, and plasma data were modeled into a two-compartment open model. Across the investigated dosage range, BMS 181184 demonstrated nonlinear, dose-dependent kinetics with enhanced clearance, reciprocal shortening of elimination half-life, and an apparently expanding volume of distribution with increasing dosage. After single-dose administration, the mean peak plasma BMS 181184 concentration (Cmax) ranged from 120 microg/ml at 10 mg/kg to 648 microg/ml at 150 mg/kg; the area under the concentration-time curve from 0 to 24 h (AUC0-24) ranged from 726 to 2,130 microg . h/ml, the volume of distribution ranged from 0.397 to 0.799 liter/kg, and the terminal half-life ranged from 4.99 to 2.31 h, respectively (P < 0.005 to P < 0.001). No drug accumulation in plasma occurred after multiple daily dosing at 10, 25, or 50 mg/kg over 15 days, although mean elimination half-lives were slightly longer. Multiple daily dosing at 150 mg/kg was associated with enhanced total clearance and a significant decrease in AUC0-24 below the values obtained at 50 mg/kg (P < 0.01) and after single-dose administration of the same dosage (P < 0.05). Assessment of tissue BMS 181184 concentrations after multiple dosing over 16 days revealed substantial uptake in the lungs, liver, and spleen and, most notably, dose-dependent accumulation of the drug within the kidneys. These findings are indicative of dose- and time-dependent elimination of BMS 181184 from plasma and renal accumulation of the compound after multiple dosing.

Animals↗
PubMed1997

Genotypic alterations in benign and malignant salivary gland tumors: histogenetic and clinical implications.

Loss of heterozygosity (LOH) and microsatellite instability (MI) were examined at 24 microsatellite loci in 46 primary benign and malignant salivary gland tumors. Among the 27 benign tumors, 11 (40.7%), manifested microsatellite alterations in at least one locus; of these, five (18.5%) showed LOH and four (14.8%) had microsatellite instability at two or more loci. Four of 11 pleomorphic adenomas (36.4%) had allele loss on the long arm of chromosome 8. Among the 19 malignant neoplasms examined, 10 (52.6%) and one (5.2%) had allele losses and MI, respectively, at multiple loci; three tumors showed MI at only one locus. Frequent LOH was detected at D8S166 (8q11-12), D17S799, and D17S122 (17p-17p11-2) loci, with an incidence of 40%, 37.5%, and 43%, respectively. In general, malignant neoplasms with LOH exhibited aggressive tumor characteristics. Statistically significant correlation's were found between LOH and pathologic classification (chi 2, p = 0.05), higher grade (p = 0.02), DNA aneuploidy (p = 0.005), and a proliferative index of > 6% (p = 0.005) of the malignant tumors. Carcinomas with 17p loci alterations, including two carcinomas expleomorphic adenoma with concurrent 8q LOH, showed more aggressive features. The results suggested that (a) loci on chromosome 8q may harbor a tumor suppressor gene or genes associated with the development or progression of some salivary neoplasms; (b) alterations on the short arm of chromosome 17 may represent an event related to tumor progression; and (c) tumors with LOH at multiple loci have aggressive biologic characteristics.

Adenoma↗
PubMed1997

Primary parotid lymphoma: the effect of International Prognostic Index on outcome.

Since the reported survival and failure-free survival (FFS) of adults with primary parotid non-Hodgkin's lymphoma (NHL) is variable, we reviewed our experience of untreated adults with primary parotid NHL. Patients were eligible if they presented to the University of Texas M. D. Anderson Cancer Center Cancer between 1980 and 1995 with parotid enlargement and if the diagnosis of lymphoma was verified according the Working Formulation. Medical records were reviewed to determine Ann Arbor Stage (AAS), the International Prognostic Index (IPI) score, response to therapy, relapse, FFS, and survival. We identified 39 untreated adults with primary parotid NHL representing 1% of all lymphomas and 8.6% of all untreated parotid neoplasms. Three patients were excluded because of suboptimal therapy, leaving 36 patients eligible for outcome analysis. Of the 18 patients with low-grade NHL, two were treated with radiotherapy, eight with chemotherapy and radiotherapy, seven with chemotherapy only, and one with antibiotics. The complete remission (CR) rate was 94%, and with a median follow-up of 36 months for surviving patients the survival and failure-free survival (FFS) at 5 years were 94% and 78%, respectively. The 5-year FFS were not statistically different between patients with early (I or II) or advanced (III or IV) AAS (83% and 74%, respectively; p > 0.05) and favorable (0 or 1) or unfavorable (> 1) IPI scores (73% and 100%, respectively; p > 0.05). All 18 patients with intermediate-grade NHL were treated with doxorubicin-based chemotherapy which was followed by radiotherapy in six. The CR rate was 89%, and with a median follow-up of 51 months for surviving patients the survival and FFS at 10 years were 80% and 72%, respectively. In this group 10-year FFS was better in early than in advanced AAS (100% vs 0%, respectively; p = 0.01) and in favorable (0 or 1) than in unfavorable (> 1) IPI scores (86% vs 20%, respectively; p < 0.01). We conclude the the FFS of patients with low-grade NHL is 78% and not affected by AAS or IPI score. The FFS of patients with intermediate-grade NHL appears comparable with that of NHLs of other primary sites, being 86% for those with IPI < or = 1 and 20% for those with IPI 1. Patients with IPI > 1 should be entered on investigational protocols aiming to increase FFS.

Adult↗
PubMed1995

Split-thickness skin graft donor site management. A randomized prospective trial comparing a hydrophilic polyurethane absorbent foam dressing with a petrolatum gauze dressing.

OBJECTIVE: Traditionally, skin graft donor sites have been covered with fine-mesh gauze dressings, and a dry eschar has been allowed to form. Newer dressings that can provide a moist wound environment may facilitate reepithelialization. We compared a hydrophilic semipermeable absorbent polyurethane foam dressing that provides a moist wound environment with a petrolatum gauze dressing for donor sites. DESIGN: Prospective randomized trial; follow-up at 14 days. SETTING: Department of head and neck surgery in a tertiary care center. PATIENTS: Sixty-eight eligible patients received one of the two dressings. Harvested skin grafts were 0.375-mm (0.015-in) thick; donor site surface areas were recorded. At postoperative day 14, the dressings were removed, and wound epithelialization was scored: 1, none; 2, scattered or spotty; and 3, complete. Donor site and operative site pain intensities were assessed by a visual numeric scale: none (0) to the worst (100) experienced over the preceding 24-hour period. Pain scores were available for 58 patients. MAIN OUTCOME MEASURES: Dressings were compared based on these criteria: healing at 14 days, infection, and donor site and operative site pain. RESULTS: A healing score of 3 was seen in 37% (14/38) of patients with hydrophilic semipermeable absorbent polyurethane foam dressings and in 17% (5/30) of patients with petrolatum gauze dressings (P = .06) by day 14. Overall, however, mean healing scores were similar in both groups. Mean healing scores for the patients who received a hydrophilic semipermeable absorbent polyurethane foam dressing was 2.3 (SD = 0.6) vs 2.2 (SD = 0.6) for patients who received the petrolatum gauze dressing (P = .20). Numbers of days required for complete epithelialization in these groups were 20.6 (SD = 10.1) and 19.3 (SD = 5.1), respectively (P = .49). One infection occurred in the group who received the petrolatum gauze dressing. The mean maximum pain intensity scores were lower for those who were given the hydrophilic semipermeable absorbent polyurethane foam dressing on postoperative days 1 through 3 (P = .003, .03, and .04, respectively). Pain increased with a larger donor site surface area for the patients with the petrolatum gauze dressing but not for the patients with the hydrophilic semipermeable absorbent polyurethane foam dressing. CONCLUSIONS: The hydrophilic semipermeable absorbent polyurethane foam dressing appears to have potential advantages over the petrolatum gauze dressing; it produces less initial patient donor site discomfort and tends to produce more complete donor site healing by postoperative day 14.

Absorption↗
PubMed1992

Experimental Trichosporon infection in persistently granulocytopenic rabbits: implications for pathogenesis, diagnosis, and treatment of an emerging opportunistic mycosis.

Disseminated Trichosporon infection, an uncommon but emerging opportunistic mycosis due to Trichosporon beigelii, is frequently difficult to diagnose, refractory to treatment, and associated with a high attributable mortality. Models of disseminated and gastrointestinal Trichosporon infection were developed in persistently granulocytopenic rabbits. The patterns of infection resembled those of clinical disease, including cutaneous lesions, chorioretinitis, renal infection, pulmonary infection, and antigenemia cross-reactive with cryptococcal capsular polysaccharide. Antigenemia, an early manifestation of disseminated Trichosporon infection, originated in vivo from a fibrillar extracellular matrix. Trichosporon organisms disseminated from the gastrointestinal tract to visceral tissue in colonized immunosuppressed rabbits, whereas there was no dissemination from the gastrointestinal tract of otherwise normal rabbits. The antifungal triazoles, fluconazole and SCH 39304, were most active; maximum tolerated doses of amphotericin B and liposomal amphotericin B were ineffective. Trichosporon antigenemia declined in response to antifungal therapy. These findings contribute to improved understanding of the pathogenesis, diagnosis, and treatment of disseminated Trichosporon infection.

Agranulocytosis↗
PubMed1990

Trichosporon beigelii, an emerging pathogen resistant to amphotericin B.

Trichosporon beigelii caused fatal disseminated infections that were resistant to amphotericin B in two granulocytopenic patients. In vitro susceptibility studies demonstrated that both index strains of T. beigelii were inhibited but not killed by amphotericin B at achievable concentrations in serum. The minimum lethal concentration for both isolates was greater than or equal to 18 micrograms/ml. Five of seven other isolates were found to have a similar pattern of amphotericin B resistance. The fact that the minimum lethal concentration of T. beigelii was many times greater than its MIC was consistent with a resistance pattern of tolerance. We concluded that T. beigelii may be resistant in vitro to amphotericin B and that this in vitro resistance was correlated with refractory, disseminated trichosporonosis in granulocytopenic patients. T. beigelii should be included in the expanding list of amphotericin B-resistant fungi.

Adolescent↗
PubMedDate not supplied

Nursery privileging for pediatric nurse practitioners.

Developing a nursery privileging policy for pediatric nurse practitioners (PNPs) in a hospital that has not previously used PNPs in this capacity requires a clear understanding of the issues, a well-thought-out plan, and a win-win approach. Current trends in privileging of PNPs are summarized. The credentialing and privileging processes are defined, and the relationships that PNPs must establish with medical and administrative staff are explored. Five steps PNPs should take before requesting nursery privileges along with approaches to managing conflict are suggested. A case example involving the creation of a nursery privileging policy is included.

Credentialing↗
PubMedDate not supplied

Pediatric practice guidelines: implications for nurse practitioners.

Practice guidelines are promoted as an important means of achieving high-quality, cost-effective health care. Nurse practitioners must understand what practice guidelines are and how they are developed and be willing to put them into practice. This discussion begins with a description of practice guidelines specific to pediatrics. The terminology used in reference to these "clinical tools" are differentiated and their historic and contemporary influences are summarized. The complexity of guideline development and attributes of a quality practice guideline are described. Finally, the pivotal roles nurse practitioners can play in putting guidelines into practice are suggested.

Acute Disease↗