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N Nicolaou

Publications and source records attributed to N Nicolaou.

At least 19 recordsLinked to original sources
PubMed2005

Comment on "Performance of different synchronization measures in real data: a case study on electroencephalographic signals".

We agree with Duckrow and Albano [Phys. Rev. E 67, 063901 (2003)] and Quian Quiroga [Phys. Rev. E 67, 063902 (2003)] that mutual information (MI) is a useful measure of dependence for electroencephalogram (EEG) data, but we show that the improvement seen in the performance of MI on extracting dependence trends from EEG is more dependent on the type of MI estimator rather than any embedding technique used. In an independent study we conducted in search for an optimal MI estimator, and in particular for EEG applications, we examined the performance of a number of MI estimators on the data set used by Quian Quiroga in their original study, where the performance of different dependence measures on real data was investigated [Phys. Rev. E 65, 041903 (2002)]. We show that for EEG applications the best performance among the investigated estimators is achieved by -nearest neighbors, which supports the conjecture by Quian Quiroga in Phys. Rev. E 67, 063902 (2003) that the nearest neighbor estimator is the most precise method for estimating MI.

Algorithms↗
PubMed2005

'Atrophic telogen effluvium' from cytotoxic drugs and a randomized controlled trial to investigate the possible protective effect of pretreatment with a topical vitamin D analogue in humans.

BACKGROUND: Hair loss from cytotoxic drugs is classically ascribed to the loss of fractured hairs (anagen effluvium). Telogen hair loss has also been described but some authors have denied any effect on the hair cycle. There are conflicting reports on a protective effect of pretreatment with a vitamin D analogue on cytotoxic drug-induced hair loss in rodents. OBJECTIVES: To investigate the process of cytotoxic hair loss and any protective effect on the hair of pretreatment with topical calcipotriol. METHODS: Breast cancer patients who were about to receive cycles of chemotherapy with cyclophosphamide 600 mg m(-2), methotrexate 40 mg m(-2) and 5-fluorouracil 600 mg m(-2) were recruited and randomized to receive calcipotriol scalp solution 50 microg mL(-1) or vehicle. The solution was applied twice daily from 4 days prior to chemotherapy and continued for 14 days in each treatment cycle. Shed, plucked and cut hairs were sampled. Absolute shed rates, the proportion of major hair types, the presence of proximal hair shaft changes, regrowth (using the new anagen hair count) and hair density were assessed. RESULTS: Ten patients receiving calcipotriol and 14 receiving vehicle completed three treatment cycles and nine from both groups completed six cycles. There was no detectable effect of calcipotriol on the proportion of patients experiencing minimal hair loss from chemotherapy, shed rates, plucked telogen and fractured hair counts, the morphology of shed and plucked hair, hair regrowth or hair density. Combining results of the treatment groups, there was a large variation in the impact of chemotherapy on hair loss, from total loss in five patients to no obvious loss in five. Excluding the latter, during chemotherapy shed telogen hairs (mean 81% of shed hairs) predominated over fractured (12%) and anagen hairs (6%) (P = 0.0002). The major pathological change was proximal hair shaft tapering, baseline mean 3% of shed hairs rising to 48% (P = 0.0005) during treatment, and there was a consequent decrease in normal telogen hairs, baseline mean 98% of all telogen hairs falling to 55% (P = 0.0005) during treatment. The pathological tapered telogen hairs had normal or small, sometimes diminutive, bulbs. Fracturing of hairs with diminutive bulbs produced typical 'exclamation mark' hairs. CONCLUSIONS: The cardinal effects of cytotoxic drugs found in this study were tapering of the proximal hair shaft and premature entry of the follicle into telogen, conflicting with the conventional view that affected hair follicles continue in anagen. There was a resulting effluvium of a mixture of tapering telogen hairs and fractured hairs. As entry into telogen is an integral part of the process, cytotoxic hair loss may be regarded as a variant of the conventional 'telogen effluvium' and we propose the term 'atrophic telogen effluvium'. There was no obvious protective effect on the hair loss of prior treatment with topical calcipotriol.

Administration, Topical↗
PubMed2003

Nail dystrophy, an unusual presentation of incontinentia pigmenti.

We describe a 57-year-old woman with a history of nail dystrophy since the age of 11 years. Multiple nail clippings were negative and multiple empirical treatments for presumed onychomycosis were unsuccessful. The patient has a daughter with classical incontinentia pigmenti. Molecular genetic analysis was positive for the NEMO gene deletion on the X chromosome, confirming the diagnosis of incontinentia pigmenti. Nail dystrophy was the sole feature of the disease in our patient.

Chromosomes, Human, X↗
PubMed2003

Venous leg ulcers after hip replacement. A clinical evaluation at 5 to 12 years.

Venous ulceration is a chronic disabling complication of deep-vein thrombosis. The aim of this study was to estimate the incidence of venous leg ulcers five years or more after total hip replacement (THR) and to investigate some of the clinical features associated with their development. We carried out a postal survey of all patients who had undergone a THR 5 to 12 years previously. Replies from 816 patients showed that 66 (8.1%) had a history of leg ulcers. The prevalence of active ulceration was 2.6% and 43 patients (5.3%) reported developing ulceration since their hip replacement. A clinical review determined that 31 (3.8%) of these were true venous ulcers. The ulcers occurred more commonly on the operated side and developed at a mean of 5.8 years (18 months to 12 years) after the first arthroplasty. A mean of 1.9 arthroplasties (1 to 5) (primary and revision) were carried out before the ulcers appeared. The overall incidence of ulcers was similar to that in the general population.

Aged↗
PubMed2002

Recursive partitioning identifies patients at high and low risk for ipsilateral tumor recurrence after breast-conserving surgery and radiation.

PURPOSE: Recursive partitioning analysis (RPA), a method of building decision trees of significant prognostic factors for outcome, was used to determine subgroups at significantly different risk for ipsilateral breast tumor recurrence (IBTR) in early-stage breast cancer. PATIENTS AND METHODS: Nine hundred twelve women underwent breast-conserving surgery, axillary dissection, and radiation. Systemic therapy was chemotherapy with or without tamoxifen in 32%, tamoxifen in 27%, or none in 41%. RPA was used to create a decision tree according to predictive variables that classify patients by IBTR risk, and the Kaplan-Meier method was used to calculate 10-year risks. Median follow-up was 5.9 years. RESULTS: Age was the first split in the partition tree. Patients more than 55 years old had a 4% 10-year IBTR, the only further division being use of tamoxifen or not (2% v 5%, P =.03). For patients </= 55 years old, extensive intraductal component (EIC) was the next significant split. For EIC-negative tumors, age </= 35 years and negative margins were associated with a 10-year IBTR of 3%; with close (</= 2 mm) or positive margins, 34%. Patients 36 to 55 years old with estrogen receptor-positive tumors receiving tamoxifen had a risk of IBTR of 5%, but had a 20% risk without tamoxifen. CONCLUSION: This RPA showed that age </= 55 versus more than 55 years was the most significant factor for IBTR. Patients </= 35 years old had a low risk of IBTR when tumors were EIC-negative with negative margins. EIC was an independent factor for IBTR for ages </= 55 years. Use of tamoxifen was the most significant factor for patients older than 55 years, but it resulted in a greater absolute decrease in risk of IBTR for patients 36 to 55 years old.

Actuarial Analysis↗
PubMed2001

Second cancers after conservative surgery and radiation for stages I-II breast cancer: identifying a subset of women at increased risk.

PURPOSE: To assess the risk and patterns of second malignancy in a group of women treated with conservative surgery and radiation in a relatively contemporary manner for early-stage invasive breast cancer, and to identify a subgroup of these women at increased risk for a second cancer. METHODS AND MATERIALS: From 1978 to 1994, 1,253 women with unilateral Stage I-II breast cancer underwent wide excision, axillary dissection, and radiation. The median follow-up was 8.9 years, with 446 patients followed for >or= 10 years. The median age was 55 years. Sixty-eight percent had T1 tumors and 74% were axillary-node negative. Radiation was directed to the breast only in 78%. Adjuvant therapy consisted of chemotherapy in 19%, tamoxifen in 19%, and both in 8%. Factors analyzed for their association with the cumulative incidence of all second malignancies, contralateral breast cancer, and non-breast cancer malignancy were: age, menopausal status, race, family history, obesity, smoking, tumor size, location, histology, pathologic nodal status, region(s) treated with radiation, and the use and type of adjuvant therapy. RESULTS: One hundred seventy-six women developed a second malignancy (87 contralateral breast cancers at a median interval of 5.8 years, and 98 non-breast cancer malignancies at a median interval of 7.2 years). Nine women had both a contralateral breast cancer and non-breast cancer second malignancy. The 5- and 10-year cumulative incidences of a second malignancy were 5% and 16% for all cancers, 3% and 7% for contralateral breast cancer, 3% and 8%, for all second non-breast cancer malignancies, and 1% and 5%, respectively, for second non-breast cancer malignancies, excluding skin cancers. Patient age was a significant factor for contralateral breast cancer and non-breast cancer second malignancy. Young age was associated with an increased risk of contralateral breast cancer, while older age was associated with an increased the risk of a second non-breast cancer second malignancy. A positive family history increased the risk of contralateral breast cancer, but not non-breast cancer malignancies. The risk of a contralateral breast cancer increased as the number of affected relatives increased. Tamoxifen resulted in a nonsignificant decrease in contralateral breast cancer and an increase in non-breast cancer second malignancies. The 5-and 10-year cumulative incidences for leukemia and lung cancer were 0.08% and 0.2%, and 0.8% and 1%, respectively. There was no significant effect of chemotherapy or the regions treated with radiation on contralateral breast cancer or non-breast cancer second malignancy. The most common types of second non-breast cancer malignancies were skin cancers, followed by gynecologic malignancies (endometrial), and gastrointestinal malignancies (colorectal and pancreas). CONCLUSION: The 10-years cumulative incidence of a second cancer in this study was 16%. Young age and family history predicted for an increased risk of contralateral breast cancer, and older age predicted for an increased risk of non-breast cancer malignancy. The majority of patients treated with conservative surgery and radiation with or without adjuvant systemic therapy will not develop a second cancer. Long-term follow-up is important to document the risk and patterns of second cancer, and knowledge of this risk and the patterns will influence surveillance and prevention strategies.

Adult↗
PubMed2001

Quantifying radiation therapy-induced brain injury with whole-brain proton MR spectroscopy: initial observations.

PURPOSE: To quantify the extent of neuronal cell loss imparted to the brain by means of radiation therapy through the decline of the amino acid derivative N-acetylaspartate (NAA) by using proton (hydrogen 1) magnetic resonance (MR) spectroscopy. MATERIALS AND METHODS: Proton MR spectroscopy in a clinical MR imager was used to ascertain the amount of whole-brain NAA before and immediately after whole-brain radiation therapy 3-4 weeks later. Eight patients (four women, four men; median age, 55 years; age range, 39-70 years) were studied. All subjects had lung cancer (non-small cell lung cancer [n = 5], small-cell lung cancer [n = 3]) and received either palliative or prophylactic whole-brain radiation therapy. Six of them also underwent a Mini-Mental Status Examination (MMSE) for correlation with the whole-brain NAA. Two-tailed Student t tests were used to evaluate the data. RESULTS: A significant (P = .042) average decline in whole-brain NAA of -0.91 mmol per person was observed in the cohort. No corresponding changes occurred in MMSE scores. There was no significant difference in whole-brain NAA decline between prophylactic and therapeutic whole-brain radiation therapy. CONCLUSION: Since whole-brain NAA loss was detected even when MMSE scores were unchanged, the former seems to be a more sensitive measure of radiation therapy injury than is the latter.

Adult↗
PubMed2001

Induction and concurrent paclitaxel/carboplatin every 3 weeks with thoracic radiotherapy in locally advanced non-small-cell lung cancer: an interim report.

The paclitaxel/carboplatin combination has demonstrated promising activity in metastatic non-small-cell lung cancer (NSCLC); therefore, we mounted an exploratory study of these agents with thoracic radiation (TRT) in locally advanced NSCLC. Eligibility stipulated a Karnofsky performance status >or= 70%, weight loss or= 2 esophagitis has corresponded to length (> 16 cm) of esophagus in the radiation treatment field (Fisher's exact test, P = 0.006). The partial response rate to induction therapy was 40% and to the combined modality therapy was 60%. The median survival for all 49 patients is 15.3 months, with a median disease-free survival (DFS) of 7.8 months. In the subset of 22 patients treated on the phase I portion of the study, the median survival and DFS were 18.5 months and 13.5 months, respectively. Induction therapy with paclitaxel and carboplatin followed by concurrent chemoradiotherapy with the same agents is an active and well-tolerated treatment approach in locally advanced NSCLC. To date, paclitaxel 175 mg/m2 plus carboplatin AUC 5 administered at 3-week intervals for 2 cycles is safe in combination with TRT.

Journal Article↗
PubMed2001

Around-the-clock attending radiology coverage is essential to avoid mistakes in the care of trauma patients.

Financial constraints due to increasing operating cost and decreased reimbursement do not allow many hospitals to maintain coverage by attending radiologists around the clock (CARAC). Preliminary film readings by radiology trainees may be inaccurate. In trauma, decisions are made fast and are often based on these preliminary readings. To examine whether there are significant discrepancies between preliminary readings (PRs) and final readings (FRs) of CT scans of trauma patients we prospectively recorded PRs (done immediately by radiology residents) and FRs (done the following working day by radiology attendings) over a period of 6 months for trauma CT scans done between 5 PM and 7 AM on weekdays or weekends. A discrepancy was classified as significant if a change in management was instituted after FR. In 42 of 383 (11%) trauma patients there was a discrepancy between PR and FR. Patients with discrepancies had a higher Injury Severity Score, higher incidence of penetrating trauma, longer hospital stay, higher hospital charges, and higher mortality than patients without any discrepancy. Most of the discrepancies were found on abdominal CT scans. The lower the level of radiology resident doing the PR the higher the likelihood of a discrepancy. In 20 patients (5%) a significant discrepancy was found. We conclude that the absence of CARAC results in inaccurate FRs risking optimal trauma patient care. The institutional savings realized by avoiding CARAC may be offset by the cost of additional care provided to patients who have delayed diagnosis and treatment due to the lack of it.

Adult↗
PubMed2000

Accuracy of the extent of axillary nodal positivity related to primary tumor size, number of involved nodes, and number of nodes examined.

PURPOSE: While a number of studies have evaluated the minimum number of axillary nodes that need to be examined to accurately determine nodal positivity or negativity, there is little information on the number of nodes which must be examined to determine the extent of nodal positivity. This study attempts to determine for patients with 1-3 positive nodes the probability that the number of positive nodes reported is the true number of positive nodes as well as the probability that 4 or more nodes could be positive based on primary tumor size and number of nodes examined. MATERIALS AND METHODS: From 1979 to 1998, 1652 women with Stages I-II invasive breast cancer underwent an axillary dissection as part of their breast conservation therapy and had more than 10 lymph nodes examined. The mean and median number of nodes identified in the dissection was 19 and 17 (range, 11-75). The median age was 55 years. A total of 1155 women had T1 tumors and 497 had T2 tumors. Of the 459 node-positive women, 72% had 1-3 positive nodes, 18% had 4-9 positive nodes, and 10% had 10 or more positive nodes. A mathematical model based on tumor size and number of nodes examined was created using the hypergeometric distribution and Bayes Theorem. The resulting model was used to estimate the accuracy of the reported number of positive nodes and the probability of 4 or more positive nodes based on various observed sampling combinations. RESULTS: For patients with T1 tumors and 1, 2, or 3 positive nodes, the minimum number of nodes examined needed for a 90% probability of accuracy is 19, 20, and 20. For T2 tumors and 1, 2, or 3 positive nodes, a minimum of 20 nodes is required. The probability of 4 or more positive nodes increases as tumor size and the number of reported positive nodes increase and as the number of examined nodes decreases. For a 10% or less probability of 4 or more positive nodes, a patient with a T1 tumor and 1, 2, or 3 observed positive nodes would require a minimum of 8, 15, and 20 nodes removed. For a T2 tumor and 1, 2, or 3 observed positive nodes, the corresponding numbers are 10, 16, and 20. CONCLUSION: The accuracy of the extent of axillary nodal positivity is influenced by the number of observed positive nodes, tumor size, and the number of nodes examined. Underestimation of the number of positive nodes will result in errors in the assessment of an individual's risk for locoregional recurrence, distant disease, and breast cancer death and will adversely impact on treatment recommendations. This model provides the clinician with a means for assessing the accuracy of the number of positive nodes reported in patients with 1-3 positive nodes.

Adult↗
PubMed2000

Internal mammary node irradiation neither decreases distant metastases nor improves survival in stage I and II breast cancer.

PURPOSE: To compare outcome for ipsilateral breast tumor recurrence (IBTR), or regional node recurrence, initial and subsequent distant metastases, and overall and cause-specific survival in women treated with conservative surgery and radiation based on whether or not radiation was targeted to the internal mammary nodes (IMN). METHODS AND MATERIALS: From 1979-1994, 1383 women with Stage I-II breast cancer underwent wide excision, axillary node dissection with >/=10 nodes removed, and radiation. Median follow-up was 6 years; median age was 55 years. A total of 114 women had radiation targeted to the IMN with deep tangents and 1269 did not. Women who received IMN treatment were more often axillary node-positive (40% vs. 25%, p = 0. 002), had central or inner quadrant tumors (61% vs. 40%, p = 0.001), and had T2 tumors (47% vs. 31%, p = 0.001). All axillary node-positive women received adjuvant chemotherapy and/or tamoxifen. For axillary node-negative women, 13% of the IMN treatment group received adjuvant systemic therapy compared to 37% of the no treatment group (p = 0.001). Radiation was directed to the breast only in 97% of the axillary node-negative women who had IMN treatment and 99% of the no IMN treatment group. For axillary node-positive women, 98% of the IMN-treated group had radiation to the breast and supraclavicular nodes +/- a posterior axillary field compared to 77% of the no IMN treatment group (p = 0.001). There were no significant differences between the two groups for median age, menopausal status, histology, final surgical margin, estrogen and progesterone receptor status, or the number of positive nodes. RESULTS: There were no significant differences in the 5- and 10-year cumulative incidence of an IBTR, regional node recurrence, initial or total distant metastases for the two groups. Similarly 5- and 10-year actuarial overall and cause-specific survival were not significantly different. However, subset analysis revealed a statistically significant increase in initial (29% vs. 15% at 10 yr, p = 0.002) and total (30% vs. 17% at 10 yr, p = 0.01) distant metastases and a significant decrease in cause-specific survival (76% vs. 89% at 10 yr, p = 0.02) for postmenopausal women who received IMN treatment. These findings could not be attributed to differences in the use of systemic therapy or the number of positive nodes. Axillary node-positive patients did not experience a significant decrease in initial (36% vs. 22% at 10 yr, p = 0.21) or total distant metastases (37% vs. 28% at 10 yr, p = 0.62) or a significant improvement in cause-specific survival (72% vs. 76% at 10 yr, p = 0.76) with IMN treatment regardless of whether the tumor was lateral or medial/central in location. IMN treatment was not associated with an increase in non-breast cancer deaths during this period of observation. CONCLUSIONS: This retrospective series was unable to identify a significant benefit for IMN irradiation in terms of distant metastases or cause-specific survival for the entire patient population, and in particular, for patients with positive axillary nodes and medially located lesions. The results of the proposed or ongoing prospective randomized trials will further address this controversial issue.

Adult↗
PubMed2000

Should internal mammary lymph nodes in breast cancer be a target for the radiation oncologist?

PURPOSE: The elective treatment of internal mammary lymph nodes (++IMNs) in breast cancer is controversial. Previous randomized trials have not shown a benefit to the extended radical mastectomy or elective IMN irradiation overall, but a survival benefit has been suggested by some for subgroups of patients with medial tumors and positive axillary lymph nodes. The advent of effective systemic chemotherapy and potential for serious cardiac morbidity have also been factors leading to the decreased use of IMN irradiation during the past decade. The recent publishing of positive trials testing postmastectomy radiation that had included regional IMN irradiation has renewed interest in their elective treatment. The purpose of this study is to critically review historical and new data regarding IMNs in breast cancer. METHODS AND MATERIALS: The historical incidence of occult IMN positivity in operable breast cancer is reviewed, and the new information provided by sentinel lymph node studies also discussed. The results of published randomized prospective trials testing the value of elective IMN dissection and/or radiation are analyzed. The data regarding patterns of failure following elective IMN treatment is studied to determine its impact on local-regional control, distant metastases, and survival. A conclusion is drawn regarding the merits of elective IMN treatment based on this review of the literature. RESULTS: Although controversial, the existing data from prospective, randomized trials of IMN treatment do not seem to support their elective dissection or irradiation. While it has not been shown to contribute to a survival benefit, the IMN irradiation increases the risk of cardiac toxicity that has effaced the value of radiation of the chest wall in reducing breast cancer deaths in previous randomized studies and meta-analyses. Sentinel lymph node mapping provides an opportunity to further evaluate the IMN chain in early stage breast cancer. Biopsy of "hot" nodes may be considered in the future to select patients who are most likely to benefit from additional regional therapy to these nodes. CONCLUSIONS: Irradiation of the IMN chain in conjunction with the chest wall and supraclavicular region should be considered only for those with pathologically proven IMNs with the goal of improving tumor regional control.

Axilla↗