Search PubMed⌕ Search

Biomedical subjects

G Gustafson

Publications and source records attributed to G Gustafson.

At least 19 recordsLinked to original sources
PubMed2001

Phase II prospective study of the use of conformal high-dose-rate brachytherapy as monotherapy for the treatment of favorable stage prostate cancer: a feasibility report.

PURPOSE: To evaluate the technical feasibility and tolerance of image-guided transperineal conformal high-dose-rate (C-HDR) brachytherapy as the sole treatment modality for favorable, localized cancer of the prostate, and to analyze possible intrafraction and interfraction volume changes in the prostate gland which may affect dosimetric quality. METHODS AND MATERIALS: Patients were eligible for this prospective Phase II trial if they had biopsy proven adenocarcinoma of the prostate with favorable prognostic factors (Gleason score < or =7, PSA < or =10 ng/ml and Stage < or =T2a). The technique consisted of a transperineal implant procedure using a template with transrectal ultrasound (TRUS) guidance. An interactive on-line real-time planning system was utilized with geometric optimization. This allowed dosimetry to be generated and modified as required intraoperatively. Prescription was to the minimum dose point in the implanted volume, assuring conformal coverage of the prostate at its widest dimension with no margin. Total dose was 3800 cGy in 4 fractions of 950 cGy each, delivered twice a day over 2 days. The dose to any segment of rectum and urethra was limited to < or =75% and < or =125% of the prescription dose, respectively. Before each fraction, needle positions were verified under fluoroscopy and adjusted as required. For the last 10 patients, the adjustments required were measured in a prospective fashion in representative extrema of the gland. TRUS images were recorded for all patients before any needle manipulation, again just before delivering the first fraction and immediately after the last fraction. This typically meant approximately 36 h to pass between the first and last measurements. Implant quality was assessed via dose-volume histograms (DVH). RESULTS: Between 3/99 and 6/00, 41 patients received C-HDR interstitial brachytherapy as their only treatment for prostate cancer at our institution. Median age was 64 years (range 51-79). Stage distribution was 27 T1c patients and 14 T2a patients. Three patients had Gleason score (GS) of 5; 34 had GS of 6; 4 patients had GS of 7. Median pretreatment PSA was 4.7 ng/ml (range 0.8-13.3). All patients tolerated the treatment well with minimal discomfort. For 23 patients, data on volume changes in the gland during the implant were tabulated. They demonstrated a mean prostate volume of 30.7 cc before any manipulation with needles, 37.0 cc at the end of fraction 1, and 38.2 cc at the end of fraction 4. In addition, for those 10 patients prospectively evaluated for required adjustments, the overall mean adjustment between fraction 1 and fraction 2 was 2.0 cm, between fraction 2 and 3 was 0.4 cm, and between fractions 3 and 4 was 0.4 cm. For 10 consecutive patients, the average prescriptions dose -D90 for fractions 1 and 4 were 104% and 100%, respectively. The corresponding average urethral D10 for fractions 1 and 4 were 122% and 132%. CONCLUSION: Our protocol using C-HDR interstitial brachytherapy as monotherapy for early cancer of the prostate was feasible and well tolerated by 41 patients treated. Changes in interfraction prostate volume do not appear to be significant enough to warrant modification of dosimetry for each fraction. Both excellent dose coverage of the prostate gland and low urethral dose are achieved as measured by DVH. However, paramount attention should be given to needle displacement before each fraction. Needle movement is most significant between fractions 1 and 2. Acute toxicity (RTOG) has been modest. Late toxicity and tumor control rates will be reported as longer follow-up allows.

Adenocarcinoma↗
PubMed2001

An opportunity for HMOs to use marketing to increase enrollee satisfaction.

PURPOSE: To identify the combination of marketing components (i.e., service, price, access, and promotion) of commercial health maintenance organizations (HMOs) that are related to overall enrollee satisfaction. The researchers focus on factors that commercial HMOs control directly--specifically, health care organization and financing. DESIGN: Descriptive (mail order). METHODOLOGY: This study uses national data provided by a major health benefits consulting firm, which collected data from a 1997 calendar year mail survey of HMO administrators. The administrators responded to an extensive survey, which tapped selected HMO marketing-mix components and the percentage of surveyed members who indicated satisfaction with their HMOs. To test hypotheses, researchers treated marketing-mix components as independent variables and enrollee satisfaction as the dependent variable. PRINCIPAL FINDINGS: This study found statistically significant relationships between overall satisfaction and HMO providers' quality; access, particularly to specialists and out-of-network providers; waiting times for physician services; customer service; and disease prevention/health promotion programs. The researchers did not find significant relationships between overall satisfaction and accreditation by the National Committee for Quality Assurance (NCQA), the presence of physician gatekeepers, numbers of providers, or financial indicators. The relationship between overall satisfaction and utilization was mixed. This study's findings are largely consistent with the literature, consumer- and professional-group position papers, and the President's Advisory Commission on Consumer Protection and Quality in the Health Care Industry. CONCLUSIONS: HMOs can use marketing as a way to address problems and pursue opportunities identified by enrollees. As these findings demonstrate, certain features of HMO design are more appealing to patients. By focusing on these preferences, HMOs can adopt a responsive market orientation that gives rise to more effective marketing mixes and hence improves enrollee satisfaction. With improved satisfaction, enrollees generate less need for government intervention through regulation or legislation.

Data Collection↗
PubMed2000

Integration of nurse executives into executive level administration in Utah hospitals.

Nurse executives (NEs) in Utah acute care hospitals perceive that they are integrated into executive level administration. This perception is shared by NEs' career supporters and hinderers. To integrate NEs, influential colleagues used active methods, especially involvement. NEs add value to the administrative team by combining clinical and managerial expertise. NE integration is manifest in decision making, participation and interaction. Continued integration depends upon commitment from the chief executive officer (CEO), leadership in organizational change, addressing "glass ceiling" issues, and NEs' continuous demonstration of competence.

Career Mobility↗
PubMed2000

Ultra-low wear rates for rigid-on-rigid bearings in total hip replacements.

With the increased clinical interest in metal-on-metal and ceramic-on-ceramic total-hip replacements (THRs), the objective of this hip simulator study was to identify the relative wear ranking of three bearing systems, namely CoCr-polyethylene (M-PE), CoCr-CoCr (M-M) and ceramic-on-ceramic (C-C). Volumetric wear rates were used as the method of comparison. The seven THR groupings included one M-PE study, two M-M studies and four C-C studies. Special emphasis was given to defining the 'run-in' phase of accelerated wear that rigid-on-rigid bearings generally exhibit. The hypothesis was that characterization of the run-in and steady state wear phases would clarify not only the tribological performance in vitro but also help correlate these in vitro wear rates with the 'average' wear rates measured on retrieved implants. The implant systems were studied on multichannel hip simulators using the Paul gait cycle and bovine serum as the lubricant. With 28 mm CoCr heads, the PE (2.5 Mrad/N2) wear rates averaged 13 mm3/10(6) cycles duration. This was considered a low value compared with the clinical model of 74 mm3/year (for 28 mm heads). Our later studies established that this low laboratory value was a consequence of the serum parameters then in use. The mating CoCr heads (with PE cups) wore at the steady state rate of 0.028 mm3/10(6) cycles. The concurrently run Metasul M-M THRs wore at the steady state rate of 0.119 mm3/10(6) cycles with high-protein serum. In the second Metasul M-M study with low-protein serum, the THR run-in rate was 2.681 mm3/10(6) cycles and steady state was 0.977 mm3/10(6) cycles. At 10 years, these data would predict a 70-fold reduction in M-M wear debris compared with the clinical PE wear model. All M-M implants exhibited biphasic wear trends, with the transition point at 0.5 x 10(6) cycles between run-in and steady state phases, the latter averaging a 3-fold decrease in wear rate. White surface coatings on implants (coming from the serum solution) were a confounding factor but did not obscure the two orders of magnitude wear performance improvement for CoCr over PE cups. The liners in the alumina head-alumina cup combination wore at the steady state rate of 0.004 mm3/10(6) cycles over 14 x 10(6) cycles duration (high-protein serum). The zirconia head-alumina cup THR combination wore at 0.174 and 0.014 mm3/10(6) cycles for run-in and steady state rates respectively (low-protein serum). The zirconia head and cup THR combination wore slightly higher initially with 0.342 and 0.013 mm3/10(6) cycles for run-in and steady state rates respectively. Other wear studies have generally predicted catastrophic wear for such zirconia-ceramic combinations. It was noted that the zirconia wear trends were frequently masked by the effects of tenacious white surface coatings. It was possible that these coatings protected the zirconia surfaces somewhat in this simulator study. The experimental ceramic Crystaloy THR had the highest ceramic run-in wear at 0.681 mm3/10(6) cycles and typical 0.016 mm3/10(6) cycles for steady state. Since these implants represented the first Crystaloy THR sets made, it was likely that the surface conditions of this high-strength ceramic could be improved in the future. Overall, the ceramic THRs demonstrated three orders of magnitude wear performance improvement over PE cups. With zirconia implants, while the cup wear was sometimes measurable, head wear was seldom discernible. Therefore, we have to be cautious in interpreting such zirconia wear data. Identifying the run-in and steady state wear rates was a valuable step in processing the ceramic wear data and assessing its reliability. Thus, the M-M and C-C THRs have demonstrated two to three orders of reduction in volumetric wear in the laboratory compared with the PE wear standard, which helps to explain the excellent wear performance and minimal osteolysis seen with such implants at retrieval operations.

Aluminum Oxide↗
PubMed2000

Enrollee satisfaction with HMOs and its relationship with disenrollment.

Relying on 1997 data from a universe of 740 HMOs, this study uniquely documented, from the perspective of health plan administrators, rates of enrollee satisfaction and disenrollments. On the basis of various reporting totals per variable or indicator, the average level of satisfaction was 83.9%; the average number of disenrollments was 20,996 per plan. Among different datasets, an average of 18.9% members disenrolled per plan; an average of 10.2% were voluntary disenrollments; and an average of 18.3% were involuntary disenrollments. Plans with higher satisfaction enrollees had predominantly lower disenrollment rates, more enrollees likely to recommend plans to family or friends, fewer older enrollees, fewer male enrollees, and higher overall plan performance. To enhance the gaining and retaining of enrollees, plan administrators should closely monitor the various dimensions of satisfaction, such as services complement, quality of care, administrative efficiency, care management, enrollees' complaints, plan performance, appointment convenience, and waiting times.

Appointments and Schedules↗
PubMed1999

Biological effects of a bifunctional DNA cross-linker. II. Generation of micronuclei and attached micronuclear-like structures.

Madin-Darby bovine kidney (MDBK) cells were treated with the bifunctional DNA cross-linker, L-7, to examine the generation of micronuclei and other nuclear abnormalities. The preceding paper demonstrates that L-7 treatment induces the formation of triradial and quadriradial chromosomes in MDBK cells. These chromosomes are believed to result from interduplex DNA cross-links formed between G-C rich centromeric satellite DNA regions on non-sister chromatids. Treatment produces a majority of centromere-positive micronuclei. In addition, many daughter cells remain attached by chromatin bridges which are sometimes beaded with micronuclei. Up to 15% of cell nuclei become lobular and fused with numerous micronuclear-like structures attached to their membranes. These attached structures are classified as attached micronuclear-like structures (AMNLS). Fluorescence in situ hybridization (FISH) using a centromeric satellite sequence was performed on treated cells. Hybridization reveals that intercellular bridges are composed of centromeric sequences and initiate at centromeric foci in daughter cells. Furthermore, the majority of junctions between AMNLS and nuclei contain an enhancement of centromeric signal. The frequency of AMNLS appears dependent on the concentration of L-7 and the duration of treatment. Similar results were found for the generation of cross-linked chromosome products in the previous paper. We suggest that AMNLS result from the abnormal mitotic segregation of cross-linked chromosome products.

Animals↗
PubMed1999

Biological effects of a bifunctional DNA crosslinker. I. Generation of triradial and quadriradial chromosomes.

Interduplex crosslinks by a bifunctional anthramycin DNA crosslinker produced triradial and quadriradial chromosomes. The crosslinker alkylates guanine at N-2. Bovine chromosomes contain GC-rich density satellite DNAs at the centromeric heterochromatin and is the basis for the formation of triradial and quadriradial chromosomes at the centromeres. The in situ crosslinking of interphase chromosomes indicates that the distance between centromeres is 17.5 A. We conclude that the nuclear matrix associated DNA in the centromeric heterochromatin of interphase chromosomes are positioned close enough for crosslinking to occur. We propose a model for the generation of triradial and quadriradial chromosomes based upon the number of interduplex crosslinks between two chromosomes.

Animals↗
PubMed1999

Use of three-dimensional radiation therapy planning tools and intraoperative ultrasound to evaluate high dose rate prostate brachytherapy implants.

PURPOSE: We performed a pilot study to evaluate the quality of high dose rate (HDR) prostate implants using a new technique combining intraoperative real-time ultrasound images with a commercially available 3-dimensional radiation therapy planning (3D RTP) system. METHODS AND MATERIALS: Twenty HDR prostate implants performed by four different physicians on a phase I/II protocol were evaluated retrospectively. Radiation therapy (RT) consisted of pelvic external beam RT (EBRT) to a dose of 46 Gy in 2-Gy fractions over 5 weeks and 2 HDR implants (prescribed dose of 950 cGy per implant). Our in-house real-time geometric optimization technique was used in all patients. Each HDR treatment was delivered without moving the patient. Ultrasound image sets were acquired immediately after needle placement and just prior to HDR treatment. The ultrasound image sets, needle and source positions and dwell times were imported into a commercial computerized tomography (CT) based 3D RTP system. Prostate contours were outlined manually caudad to cephalad. Dose-volume histograms (DVHs) of the prostate were evaluated for each implant. RESULTS: Four patients with stage T2a carcinoma, 4 with stage T2b, and 3 with stage T1c were studied. The median number of needles used per implant was 16 (range 14-18). The median treated volume of the implant (volume of tissue covered by the 100% isodose surface) was 82.6 cc (range 52.6-96.3 cc). The median target volume based on the contours entered in the 3D RTP system was 44.83 cc (range 28.5-67.45 cc). The calculated minimum dose to the target volume was 70% of the prescribed dose (range 45-97%). On average 92% of the target volume received the prescribed dose (range 75-99 %). The mean homogeneity index (fraction of the target volume receiving between 1.0 to 1.5 times the prescribed dose) was 80% or 0.8 (range 0.55-0.9). These results compare favorably to recent studies of permanent implants which report a minimum target volume dose of 43% (range 29-50%) and an average of 85% of the target volume (range 76-92%) receiving the prescribed dose. CONCLUSIONS: The feasibility of evaluating HDR prostate implants using ultrasound images (acquired immediately prior to treatment) with a commercially available 3D RTP system was established. The dosimetric characteristics of these HDR implants appear to be substantially different compared to permanent implants. These developments allow quantitative evaluation of the dosimetric quality of HDR prostate treatments. Future studies will examine any correlation between the dosimetric quality of the implant and clinical/biochemical outcomes.

Brachytherapy↗
PubMed1999

Irradiation of the tumor bed alone after lumpectomy in selected patients with early-stage breast cancer treated with breast conserving therapy.

BACKGROUNDS AND OBJECTIVES: We present the interim findings of our in-house protocol treating the tumor bed alone after lumpectomy with low-dose-rate (LDR) interstitial brachytherapy in selected patients with early-stage breast cancer treated with breast conserving therapy (BCT). METHODS: From 1 March 1993 through 1 January 1995, 50 women with early-stage breast cancer were entered into a protocol of tumor bed irradiation alone using an interstitial LDR implant. Patients were eligible if their tumor was an infiltrating ductal carcinoma < or =3 cm in diameter, surgical margins were clear by at least 2 mm, the tumor did not contain an extensive intraductal component, the axilla was surgically staged with < or =3 nodes involved with cancer, and a postoperative mammogram was performed. Implants were positioned using a template guide delivering 50 Gy over 96 hr to the lumpectomy bed plus a 1-2-cm margin. Local control, cosmetic outcome, and complications were assessed. RESULTS: Patients ranged in age from 40 to 84 years (median, 65). The median tumor size was 10 mm (range, 1-25). Seventeen of 50 patients (34%) had well-differentiated tumors, 22 (44%) had moderately differentiated tumors, and in 11 (22%) the tumor was poorly differentiated. Forty-five patients (90%) were node-negative while five (10%) had 1-3 positive nodes. A total of 23 (46%) patients were placed on tamoxifen and 3 (6%) received adjuvant systemic chemotherapy. No patient was lost to follow-up. The median follow-up for surviving patients is 47 months (range, 37-59). No patient has experienced a local, regional, or distant failure. Three patients have died at 19, 33, and 39 months after treatment. All were without clinical evidence of recurrent disease and all deaths were unrelated to treatment. Good-to-excellent cosmetic results have been observed in 49 of 50 patients (98%) (median cosmetic follow-up was 44 months with a range of 19-59). No patient has experienced significant sequelae related to their implant. CONCLUSIONS: Interim results with treatment of the tumor bed alone with an LDR interstitial implant appear promising. Long-term follow-up of these patients and additional studies will be necessary to establish the equivalence of this treatment approach compared to standard BCT.

Adult↗
PubMed1999

Effectiveness of nurse executives: measurement of role factors and attitudes.

This article describes the outcome of a survey of 40 nurse executives and 56 influential colleagues. Both groups agreed that leadership was the most important quality for the executive role. The nurses' primary focus was resolution of patient care problems. Influential colleagues stated resource allocation and initiation of change were two qualities needing improvement. The nurses rated themselves high in confidence about their job responsibilities, scored relationships as the most satisfying attribute, and cited provision of quality health care as the greatest advantage of their position. The greatest disadvantage was lack of administrative support. The results suggest the educational preparation needed for nurse executives.

Attitude of Health Personnel↗
PubMed1998

Spatial reproducibility of the ring and tandem high-dose rate cervix applicator.

PURPOSE: High-dose rate (HDR) applicators for uterine cervix brachytherapy are used with increasing frequency. Because multiple HDR fractions are required for treatment, the applicator position reproducibility is of most importance. To study this effect, the clinical data from patients with uterine cervix cancer were examined retrospectively to evaluate the interfraction geometric variation of the HDR applicator and its potential treatment impact. METHODS AND MATERIALS: Eighteen patients with invasive cervical cancer who were treated with definitive radiotherapy at William Beaumont Hospital were included in the study. Patients were treated with 45-50.4 Gy megavoltage external beam to the pelvis, and 35 Gy to the prescription point A from 7 fractions of HDR brachytherapy. The 3-dimensional (3D) interfraction geometrical variation of the ring and tandem (R & T) applicator was measured using predefined reference points in the 7 sets of orthogonal simulation films obtained prior to each HDR application. Spatial reproducibility of the R & T insertion and time-trend of the R & T position variation related to patient's anatomy during the treatment course were analyzed with respect to different groups of patients who had either early or advanced disease. RESULTS: The translational variation of the applicator position for all patients was 6.5, 5.9, and 7.7 mm (one standard deviation), respectively, in the patient's superior-to-inferior (SI), right-to-left lateral (RL), and anterior-to-posterior (AP) direction. The rotational variation was 3.4, 4.6, and 6.0 degrees (one standard deviation) in the patient's coronal, transverse, and sagittal planes. When the patients were grouped based on early disease or advanced disease, the latter demonstrated substantially larger variation (factor of 2) in the applicator position than the former. Furthermore, the time-trend of position variation was observable for both groups of patients. The variations occurred primarily during the first 3 fractions. CONCLUSIONS: Based on the good spatial reproducibility observed in our study, the current clinical procedure for the HDR R & T applicator placement is reliable. Positional reproducibility of the R & T applicator is highly dependent upon the size of tumor volume, which, in turn, deviates the applicator during the early course of HDR brachytherapy. Attention to the construction of the midline block is of paramount importance.

Brachytherapy↗
PubMed1998

Nurse executives' leadership roles. Perceptions of incumbents and influential colleagues.

The authors present a leadership profile of employed nurse executives (NEs). Interviews and survey data show that the typical NE is a married, middle-aged woman who has a masters degree in clinical nursing and extensive clinical experience. When comparing NEs' and influential colleagues' perceptions of the effectiveness of NEs leadership skills, the former rate themselves higher than the latter, and both groups perceive that NEs' leadership styles are more "task motivated" than "relationship motivated." The authors apply these findings to the career planning of NEs, chief executive officers, and educators in healthcare fields.

Adult↗
PubMed1998

Academic preparation for healthcare executive-track personnel.

This study focuses on career aspirations of executive-track health care administrative personnel and their perceptions of the competencies required to become hospital chief executive officers (CEOs). This article examines these topics using the results of a 1994 survey of 162 junior- and mid-level healthcare managers who work in hospitals in a western state. Respondents included 34 CEO aspirants and 128 CEO nonaspirants. The majority of both groups reported high satisfaction with several work-related activities. Significantly more CEO nonaspirants than CEO aspirants perceived a need for additional self-development in several work areas. CEO aspirants reported that CEOs five years from now would need improved strategy formulation and negotiation skills. CEO aspirants also perceived that in the future, successful CEOs will have to be more proficient in several areas, such as interpersonal skills and medical staff relations. Three lists of academic subject matter considered important to career preparation were generated from (1) the Association of University Programs in Health Administration (AUPHA) undergraduate standards, combined with curriculum graduate standards of the Accrediting Commission on Education for Health Services Administration (ACEHSA); (2) study participants' responses; and (3) professional literature. When compared for relatedness, the contents of the three lists were not significantly different statistically. The implications of these findings for health administration education are discussed.

Adult↗
PubMed1997

Hospital administrators' career paths: which way to the top?

This article examines career paths of aspirants to hospital administrator positions. It focuses on successful career objectives, barriers, and paths. The 1994 survey data from 162 hospital-employed executive track personnel in a western state facilitate comparisons with nonaspirants. Only 34 (21 percent) self-reported a goal to become an administrator. Aspirants require institutional and mentor support, and need to follow more proactive and diverse career paths than they have done previously.

Adult↗
PubMed1996

Identification of a new antifungal target site through a dual biochemical and molecular-genetics approach.

The target site of the antifungal compound LY214352 [8-chloro-4-(2-chloro-4-fluorophenoxy) quinoline] has been identified through a dual biochemical and molecular-genetics approach. In the molecular-genetics approach, a cosmid library was prepared from an Aspergillus nidulans mutant that was resistant to LY214352 because of a dominant mutation in a single gene. A single cosmid (6A6-6) that could transform an LY214352-sensitive strain of A. nidulans to LY214352-resistance was isolated from the library by sib-selection. Restriction fragments from cosmid 6A6-6 containing the functional resistance gene were identified by transformation, and sequenced. The LY214352-resistance gene coded for a protein of 520 amino acids that had a 34% identity and a 57% similarity in a 333 amino-acid overlap to E. coli dihydroorotate dehydrogenase (DHO-DH). The results of a series of biochemical mechanism-of-action studies initiated simultaneously with molecular-genetic experiments also suggested that DHO-DH was the target of LY214352. Assays measuring the inhibition of DHO-DH activity by LY214352 in a wild-type strain (I50=40 ng/ml) and a highly resistant mutant (I50>100 microgram/ml) conclusively demonstrated that DHO-DH is the target site of LY214352 in A. nidulans. Several mutations in the DHO-DH (pyrE) gene that resulted in resistance to LY214352 were identified.

Antifungal Agents↗
PubMed1996

Pathologic and mammographic findings predicting the adequacy of tumor excision before breast-conserving therapy.

OBJECTIVE: We performed a retrospective review to determine the need for reexcision after excisional biopsy in patients with breast cancer who were treated with breast-conserving therapy. MATERIALS AND METHODS: Eighty-seven patients with infiltrating ductal carcinoma of the breast underwent excisional biopsy followed by reexcision of the tumor site. Reexcision specimens were evaluated for residual disease and correlated with initial mammographic and pathologic findings. RESULTS: Tumors with an extensive intraductal component (EIC) were more likely to have residual disease at reexcision than those without an EIC (65% versus 6%, p < .01). Initially positive margins did not predict residual disease at reexcision significantly better than did initially negative margins (29% versus 13%, p = .08). Suspicious mammographic calcifications, absence of a discernible mass detected mammographically, or both were associated with a significantly increased risk of residual disease at reexcision. By combining all features (EIC, margin status, and mammography), we found that subsets of patients had significantly different risks of residual disease, which ranged from 6% to 83% (p < .01). CONCLUSION: Mammographic and pathologic findings are useful in predicting the adequacy of breast resection before radiation therapy in patients treated with breast-conserving therapy. An EIC is the most useful predictor of residual disease at reexcision. When combined, EIC, margin status, and mammographic findings form a powerful tool to judge the need for reexcision before radiation therapy.

Adult↗