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Biomedical subjects

K R Stevens

Publications and source records attributed to K R Stevens.

At least 19 recordsLinked to original sources
PubMed2000

Cranial neuropathy following curative chemotherapy and radiotherapy for carcinoma of the nasopharynx.

Cranial nerve damage following head and neck radiotherapy is an unusual event. Cranial neuropathy following concurrent chemotherapy and radiotherapy is unreported. The authors report a case of a 54-year-old man treated with curative chemotherapy and radiotherapy for a stage III nasopharyngeal carcinoma who developed an unilateral hypoglossal nerve palsy five years after therapy. Follow-up examination and magnetic resonance imaging (MRI) show no evidence of recurrent disease. Hypoglossal nerve injury occurring after head and neck radiotherapy is an indirect effect due to progressive soft tissue fibrosis and loss of vascularity. This process develops over years leading to nerve entrapment and permanent damage. Cranial nerve palsies, including damage to the hypoglossal nerve, can develop years after therapy with no evidence of tumour recurrence. Chemotherapy and radiotherapy have improved progression-free and overall survival in advanced nasopharyngeal cancer. As more patients achieve long-term tumour control following chemotherapy and radiotherapy, we must be cognizant of potential late injury to cranial nerves.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1999

Localization of the apex of the vagina: implications for radiation therapy planning.

PURPOSE: To evaluate (a) the displacement of the vaginal apex by a rod during radiation therapy simulation for gynecologic malignancy and (b) apical localization with implanted radiopaque markers. MATERIALS AND METHODS: Metallic markers were implanted in the cervix or vaginal cuff in nine patients with cervical or endometrial carcinoma who underwent irradiation. In all but one patient, radiographs were obtained with and then without the vaginal rod. Displacement of the markers relative to bone landmarks was measured. The total displacement was the square root of the sum of the squares of displacement in each axial direction. RESULTS: All patients showed displacement of the cervical markers by the vaginal rod (mean total displacement, 1.9 cm; range, 0.6-3.6 cm). The greatest displacement was cephalic (mean, 1.5 cm; range, 0.5-2.4 cm). Anteroposterior displacement occurred in all patients but was not as predictable as cephalic displacement. Displacement was anterior in five of the eight patients, posterior in three patients, and lateral in four patients. CONCLUSION: Displacement of the vaginal apex and/or cervix with placement of the vaginal rod during simulation was marked in all patients. Use of implanted cervical markers to localize the vaginal apex or the cervix during simulation is more accurate than use of a vaginal rod.

Adult↗
PubMed1999

Metastasis stage, adjuvant treatment, and residual tumor are prognostic factors for medulloblastoma in children: conclusions from the Children's Cancer Group 921 randomized phase III study.

PURPOSE: From 1986 to 1992, "eight-drugs-in-one-day" (8-in-1) chemotherapy both before and after radiation therapy (XRT) (54 Gy tumor/36 Gy neuraxis) was compared with vincristine, lomustine (CCNU), and prednisone (VCP) after XRT in children with untreated, high-stage medulloblastoma (MB). PATIENTS AND METHODS: Two hundred three eligible patients with an institutional diagnosis of MB were stratified by local invasion and metastatic stage (Chang T/M) and randomized to therapy. Median time at risk from study entry was 7.0 years. RESULTS: Survival and progression-free survival (PFS) +/- SE at 7 years were 55%+/-5% and 54%+/-5%, respectively. VCP was superior to 8-in-1 chemotherapy, with 5-year PFS rates of 63%+/-5% versus 45%+/-5%, respectively (P = .006). Upon central neuropathology review, 188 patients were confirmed as having MB and were the subjects for analyses of prognostic factors. Children aged 1.5 to younger than 3 years had inferior 5-year estimates of PFS, compared with children 3 years old or older (P = .0014; 32%+/-10% v 58%+/-4%, respectively). For MB patients 3 years of age or older, the prognostic effect of tumor spread (MO v M1 v M2+) on PFS was powerful (P = .0006); 5-year PFS rates were 70%+/-5%, 57%+/-10%, and 40%+/-8%, respectively. PFS distributions at 5 years for patients with M0 tumors with less than 1.5 cm2 of residual tumor, versus > or = 1.5 cm2 of residual tumor by scan, were significantly different (P = .023; 78%+/-6% v 54%+/-11%, respectively). CONCLUSION: VCP plus XRT is a superior adjuvant combination compared with 8-in-1 chemotherapy plus XRT. For patients with M0 tumors, residual tumor bulk (not extent of resection) is a predictor for PFS. Patients with M0 tumors, > or = 3 years with < or = 1.5 cm2 residual tumor, had a 78%+/-6% 5-year PFS rate. Children younger than 3 years old who received a reduced XRT dosage had the lowest survival rate.

Adolescent↗
PubMed1999

Evidence-based practice and perioperative nursing.

The implementation of evidence-based practice in perioperative nursing holds promise of improving quality of care and client outcomes. Several factors within health care have precipitated an emphasis on evidence-based practice. The use of research results in clinical decisions is recommended as the basis of nursing practice of the future. To assist with development of evidence-based practice in nursing, basic steps of the process are presented. In addition, strategies for locating existing evidence-based practice guidelines and resources are described. Perioperative nurse researchers and practice leaders should move this issue into a top priority for the specialty.

Evidence-Based Medicine↗
PubMed1998

A c-rasHa mutation in the metastasis of a human papillomavirus (HPV)-18 positive penile squamous cell carcinoma suggests a cooperative effect between HPV-18 and c-rasHa activation in malignant progression.

BACKGROUND: Human papillomaviruses (HPV) have been implicated in the etiology of anogenital squamous epithelial tumors. Of the 65 HPV strains, subtypes HPV-16 and HPV-18 frequently are associated with malignant conditions and are capable of transforming keratinocytes in vitro. However, additional cellular changes are necessary to confer tumorigenicity to HPV-infected cells. Secondary events implicated in the progression to malignancy include loss of tumor suppressor genes such as p53 and/or activation of cellular oncogenes such as c-rasHa. METHODS: Polymerase chain reaction (PCR) was used to identify HPV-16 or HPV-18 genetic sequence in primary penile squamous cell carcinoma and two inguinal lymph node metastases. p53 and c-rasHa loci were analyzed by sequencing of PCR-amplified genomic DNA. RESULTS: HPV-18 but not HPV-16 infection was found in the primary carcinoma and in inguinal metastases occurring 5 and 7 years after the initial lesion. Sequence analysis did not identify any p53 mutations in the primary carcinoma or its metastases. However, although the primary lesion and the 5-year metastasis encoded wild-type c-rasHa, the 7-year metastasis had a missense mutation within c-rasHa codon 61. CONCLUSIONS: To the authors' knowledge, this is the first report of an activating c-rasHa mutation associated with squamous cell carcinoma of the penis. The presence of activated c-rasHa in the second metastasis but not in the first metastasis or the primary lesion suggests that activation of c-rasHa may be a late event in the malignant progression of HPV-18-associated penile squamous cell carcinoma. Analysis of additional samples from primary lesions and their resultant metastases is necessary to elucidate the incidence and significance of c-rasHa activation in penile squamous cell carcinoma.

Carcinoma, Squamous Cell↗
PubMed1998

Intercellular adhesion molecule-1 and leukocyte function-associated antigen-3 provide costimulation for superantigen-induced T lymphocyte proliferation in the absence of a specific presenting molecule.

Bacterial superantigens can bind TCR in the absence of MHC class II molecules and activate T lymphocytes when cocultured with certain class II-deficient accessory cells. It has not been determined, however, whether these accessory cells provide direct costimulation to the T cell or serve to present superantigens via a nonconventional ligand. We have identified a human adenocarcinoma cell line, SW480, that assists in the activation of human T cells by the staphylococcal enterotoxins B (SEB), C1 (SEC1), and D (SED), but not SEA, SEC2, SEC3, or SEE. SW480 cells did not express class II molecules, and anti-class II mAbs did not inhibit T cell proliferation, supporting the hypothesis that class II is not absolutely required for enterotoxin-mediated T cell activation. The TCR Vbeta profile of T cells stimulated by SEB plus SW480 cells was similar to that of T cells stimulated by SEB plus class II+ APC, indicating that TCR-SEB interactions were preserved in the absence of class II molecules. Binding studies failed to detect specific association of SEB with SW480 cells, suggesting that SW480 cells do not express receptors for enterotoxin. SEB coupled to beads, however, stimulated T cell proliferation, but only in the presence of SW480 cells. SW480 cells express both ICAM-1 and LFA-3 molecules, and the addition of Abs to these receptors inhibited T cell proliferation. These findings support a model in which certain enterotoxins engage the TCR independent of MHC class II or other specific presenting molecules and induce T cell proliferation with signals provided by nonconventional accessory cells.

Adenocarcinoma↗
PubMed1998

Survival and prognostic factors following radiation therapy and chemotherapy for ependymomas in children: a report of the Children's Cancer Group.

OBJECT: Ependymomas in children continue to generate controversy regarding their histological diagnosis and grading. optimal management, and possible prognostic factors. To increase our knowledge of these tumors the authors addressed these issues in a cohort of children with prospectively staged ependymomas treated with radiotherapy and chemotherapy. METHODS: Children between the ages of 2 and 17.3 years harboring an intracranial ependymoma confirmed by a central review of the tumor's pathological characteristics were treated according to Children's Cancer Group Protocol 921 from 1986 to 1992. Treatment following surgery and postoperative tumor staging (including brain computerized tomography or magnetic resonance [MR] imaging, spinal MR imaging or myelography, and cerebrospinal fluid cytological investigation) included craniospinal irradiation with a local boost to the primary tumor and patient randomization to receive adjuvant chemotherapy with either 1) CCNU, vincristine, and prednisone, or 2) the eight-drugs-in-1-day regimen. Centralized review of the tumor pathological characteristics revealed 20 ependymomas and 12 anaplastic ependymomas in the 32 children included in the study. Diagnoses made at the individual institutions included anaplastic (malignant) ependymoma (15 patients), ependymoma (four patients), ependymoblastoma (nine patients), ependymoastrocytoma (one patient), and primitive neuroectodermal tumor (three patients), which were discordant with the centralized review diagnosis in 22 of 32 cases. Only three of the 32 patients had metastatic disease (two with M and one with M3 stages). At surgery, 47% of tumors were estimated to be totally resected. Among the 14 of 17 patients who suffered a relapse and were evaluated for site of relapse, 10 (71%) had an isolated local relapse, three (21%) had concurrent local and metastatic relapse, and only one (7%) had an isolated metastatic relapse. Kaplan-Meier estimates of 5-year progression-free survival (PFS) and overall survival rates were 50 +/- 10% and 64 +/- 9%, respectively. CONCLUSIONS: Predictors of PFS duration included an estimate of the extent of resection made at surgery (total compared with less than total, p = 0.0001) and the amount of residual tumor on postoperative imaging as verified by centralized radiological review (< or = 1.5 cm2 compared with > 1.5 cm2, p < 0.0001). No other factors, including centrally reviewed tumor histopathological type, location, metastasis and tumor (M and T) stages, patient age, race, gender, or chemotherapy treatment regimen significantly correlated with PFS duration. The pattern of predominantly local relapse and the important influence of residual tumor or the extent of resection on PFS duration confirms a prevailing impression that local disease control is the major factor in the prediction of outcome of ependymoma. Survival rates were comparable with those reported by other investigators who have treated patients with similar doses of radiation and no chemotherapy.

Adolescent↗
PubMed1997

Cultural consideration in promoting wellness.

This article discusses culture as it relates to the cardiovascular health promotion needs of various cultural groups. The promotion of cardiovascular wellness among cultural groups can be facilitated by the use of culturally appropriate models, interventions, and strategies. Those major characteristics that extend across cultures that may guide cardiovascular nurses in providing culturally appropriate care include communication, family and kinship models, and access to and acceptance of medical involvement in health care matters.

Cardiovascular Diseases↗
PubMed1996

Altered orientation of streptococcal superantigen (SSA) on HLA-DR1 allows unconventional regions to contribute to SSA Vbeta specificity.

Crystallographic studies reveal even distantly related bacterial superantigens (SAg) to adopt a common structural topology. Mutational analyses confirm that this shared folding pattern often confers a conserved function to analogous residues in different SAg, albeit with specificities for particular TCR or MHC class II molecules. It was thus surprising that the streptococcal SAg SSA differed from related SAg in the location of its Vbeta-determining residues. Because it seemed unlikely that SSA would deviate significantly from an SAg-like topology, we hypothesized that variations in SSA Vbeta-determining regions might result from differences in SSA-MHC class II interactions relative to other SAg during SSA presentation to the TCR. Comparison of the DR1-binding properties of SSA with its closest homologue SEB found different amino acid positions within SAg primary sequences to contribute to SSA-DR1 and SEB-DR1 interactions, and suggested that SSA bound DR1 with an altered orientation relative to SEB. The common involvement of DR1 alpha39K, however, predicted that the two SAg bound overlapping sites on DR1. Nevertheless, SSA and SEB did not effectively cross-compete for DR1 binding and had opposite patterns of DR1-binding affinity in the presence of distinct DR1-expressing cell lines. The data thus suggest that SSA and SEB bind not only with different orientations on DR1, but may bind preferentially to distinct DR1 subsets delineated by cell-specific factors. Differences in orientation of SSA on DR1 and/or interaction of SSA with particular DR1 subsets may explain why unconventional regions influence SSA TCR Vbeta specificity.

Animals↗
PubMed1996

Species-dependent post-translational modification and position 2 allelism: effects on streptococcal superantigen SSA structure and V beta specificity.

Epidemiologic and molecular population genetic analyses support a role for superantigens (SAg) in the pathogenesis of severe staphylococcal and streptococcal infections. To investigate how variations in SAg structure influence immunomodulatory activity, we examined the biochemical and functional properties of two allelic variants of streptococcal SAg SSA that differ at position 2. Mass spectrometry revealed both recombinant (Escherichia coli) and native (Streptococcus pyogenes) SSA allelic variants to have significantly larger molecular masses than predicted by primary sequence alone and provided evidence that the proteins were modified by the addition of biochemical moieties, a phenomenon that has not been described for related SAg. Furthermore, the molecular masses of native and recombinant SSA were not the same; SSA was differentially post-translationally modified by the two bacterial genera. The substitution of E. coli-dependent processing for that of S. pyogenes altered both protease digestion and V beta specificity, suggesting that recombinant SAg from E. coli may not accurately represent the native toxin. In addition, the observation that SSA allelic variants differed in V beta specificity supports a role for position 2 in SSA-TCR interactions. That SSA position 2 contributes to V beta specificity could not have been predicted from functional or crystallographic studies of other SAg and suggests that SSA may adopt unique interactions with TCR and/or MHC class II molecules. Determining the structural basis for these differences should offer additional clues to the manner in which SAg exert their effects on the immune system during infection and may allow the designing of SAg mutants with specific quantitative and qualitative immunomodulatory properties.

Alkylation↗
PubMed1996

Squamous cell carcinoma of the pharyngeal walls treated with radiotherapy.

PURPOSE: To assess the impact of fractionation schedule, chemotherapy, and tumor location on local control and survival in patients treated with definitive irradiation for carcinoma of the pharyngeal walls. METHODS AND MATERIALS: Between May 1971 and December 1991, 74 patients with previously untreated squamous cell carcinoma of the pharyngeal walls (excluding nasopharynx, tonsil, and pyriform sinus) were treated with radical megavoltage irradiation with or without chemotherapy at Oregon Health Sciences University. RESULTS: Two-year local control rates by stage were: T1: 100%, T2: 55%, T3: 31%, and T4: 29% . Twice-a-day irradiation improved local control rates as compared with once-a-day irradiation for patients with Stage T3 lesions, with 5 out of 7 (71.4%) vs. 4 out of 19 (21%) patients controlled at 2 years (p = 0.015). No improvement was seen in 2-year local control of all stages when chemotherapy was used in conjunction with once-a-day fractionation; however, six of eight patients (75%) treated with twice-a-day irradiation combined with either induction or concurrent chemotherapy had local control. The 2-year local control rate of 100% (6 out of 6) for the group of patients treated with concurrent chemotherapy and b.i.d. irradiation (all with Stage T3 and T4 tumors) is a dramatic improvement over the 2-year local control rate of 30% (10 out of 33) for our entire group of patients with Stage T3 and T4 tumors. Local control rates did not differ by tumor location on the pharyngeal walls. Adjusted disease-specific survival rates by stage were: 1: 100%, II: 85%, III: 58%, IV: 40%. Overall survival rates by stage were: I: 75%, II: 67%, III: 33%, IV: 30%. CONCLUSION: We advocate radical irradiation as the primary therapy for pharyngeal wall carcinomas with the use of twice-a-day fractionation for Stages T2-T4. Our preliminary results with concurrent chemotherapy and b.i.d. irradiation for advanced T3 and T4 tumors appear to be comparable to reported results with hyperfractionated radiation alone. The relative contribution of chemotherapy to b.i.d. irradiation cannot be determined from this small retrospective series; however, in view of the relatively poor results for patients with advanced stage disease, we feel this treatment combination deserves further investigation.

Adolescent↗
PubMed1996

Assessment, etiology, and intervention in obesity in children.

Obesity is a common nutritional disturbance of children and affects 25% to 30% of children and adolescents. This paper examines obesity in childhood, the measurement of obesity in children, and the relationship of obesity to coronary heart disease risks and discusses weight reduction issues in children. Clinically useful definitions of obesity in children have not been established, although the body mass index, together with anthropometric measurements, may provide the practitioner with useful assessment parameters. Discussions of weight in children must acknowledge the nutritional requirements of the normally occurring growth process. Because growth (and subsequently weight) varies widely among children even of the same age, measurement, classification, and control of weight must take into account the growth process and growth requirements. Interventions in childhood obesity should be directed toward family involvement in the chosen strategy and nutritional prudence coupled with typical activity.

Adolescent↗
PubMed1995

Survival and prognostic factors following radiation and/or chemotherapy for primitive neuroectodermal tumors of the pineal region in infants and children: a report of the Childrens Cancer Group.

PURPOSE: To describe the biologic and clinical features of children with primitive neuroectodermal tumors (PNETs) arising in the pineal region (pineoblastomas) and evaluate prospectively the efficacy of radiation therapy (RT) and/or chemotherapy. PATIENTS AND METHODS: Between 1986 and 1992, 25 children with PNETs of the pineal region were treated as part of a Childrens Cancer Group study. Eight infants less than 18 months of age were nonrandomly treated with eight-drugs-in-1-day chemotherapy without RT. The remaining 17 patients were treated with craniospinal RT and randomized to receive either vincristine, lomustine (CCNU), and prednisone or the eight-drugs-in-1-day regimen. RESULTS: Of 24 completely staged patients, 20 (83%) had localized disease at diagnosis. All infants developed progressive disease a median of 4 months from the start of treatment. Of the 17 older patients treated with RT and chemotherapy, the Kaplan-Meier estimate of progression-free survival (PFS) at 3 years is 61% +/- 13%. This is superior to the PFS of children with other supratentorial PNETs (P = .026). Following RT, 12 of 17 patients (70.6%) had a residual pineal region mass, which persisted for as long as 5 years before resolving; only four subsequently developed progressive disease. CONCLUSION: (1) Eight-in-1 chemotherapy without RT appears to be ineffective therapy for young children with PNETs of the pineal region. (2) For children more than 18 months of age at diagnosis treated with craniospinal RT and chemotherapy, the PFS is superior to that of children with other supratentorial PNETs. (3) A residual enhancing mass following RT is not predictive of treatment failure.

Adolescent↗
PubMed1994

High-dose reirradiation of head and neck cancer with curative intent.

PURPOSE: This study evaluates the response of new or recurrent head and neck cancers and the response of associated normal tissues to high dose reirradiation with curative intent. METHODS AND MATERIALS: From 1964 to 1991, 15 patients with in-field new second head and neck cancers and 85 patients with recurrent head and neck cancers have had high-dose reirradiation that overlapped with previously irradiated volumes. Reirradiation was given only to patients with no more than apparent minimal clinical radiation effects from the first radiation course. The reirradiation consisted of external beam only in 82 patients, external beam plus intracavitary or interstitial implant irradiation in 14 patients, and interstitial implant irradiation only in four patients. The combined overlapping dose from both the initial and subsequent irradiation (including brachytherapy) was 69-89 Gy in 14 patients, 90-99 Gy in 15 patients, 100-119 Gy in 27 patients, and 120 Gy or greater in 44 patients. Four patients had areas of overlap that received greater than 180 Gy. RESULTS: The actuarial 5-year survival was 37% for patients with new second primary cancers and 17% for patients with recurrent cancers. Loco-regional tumor control was achieved in 60% of the patients with new tumors and in 27% of the patients with recurrent tumors. Nine of the 100 patients developed severe adverse normal tissue effects from the reirradiation. CONCLUSION: High-dose reirradiation of head and neck cancers can be successful curative treatment in a significant proportion of patients. It is associated with substantial but acceptable risks in properly selected patients.

Dose-Response Relationship, Drug↗
PubMed1994

Patents and the nurse scholar, Part I: The basic philosophy of intellectual property.

Patenting intellectual property is important for a number of reasons. Health care products are designed to improve the effectiveness and efficiency of care. Without the patent, the property would most likely never enter into the public market for general use by either health care providers or clients. Products such as the specialized IV pole which also accommodates dependent drains (e.g. urinary drainage bags) (Rebar, 1991) or the premature infant pacifier (Engebretson & Wardell, 1991) are valuable assets to patient care. However, without patents to protect them as property, their value in the commercialization process would be nil. Therefore, the public benefits from this system for three reasons: (1) it encourages the inventor to make the invention; (2) the public is given the opportunity to use the invention; (3) the knowledge of the invention is made available to everyone; and (4) often royalties are returned to the institution for further research and development activities.

Clinical Nursing Research↗