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Results for “recurrence timing”

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PubMed1988

Perioperative blood transfusions are associated with decreased time to recurrence and decreased survival after resection of colorectal liver metastases.

Data from fifty-five patients who had hepatic resections for colorectal liver metastases at the National Cancer Institute (NCI) were analyzed to determine the effect of perioperative blood transfusions on disease recurrence and overall survival. Besides blood transfusions, other factors included in the analysis were size, number, and distribution of metastases, margin status of resected metastases, length of disease-free interval, Duke's stage of the primary tumor, type of hepatic resection, and anesthesia time. Using the Cox proportional hazards model, the amount of blood transfused was found to be a significant prognostic factor. For each additional unit of blood transfused the risk of disease recurrence and death was increased by 5% (p = 0.0015) and 7% (p = 0.0013), respectively. The median disease-free survival for patients who received 3-5, 6-10, and greater than or equal to 11 transfused units was 26, 12.1, and 11.4 months, respectively. The median overall survival for patients who received 3-5, 6-10, and greater than or equal to 11 transfused units was greater than 44, 39.2, and 33.6 months, respectively. The number of resected nodules (1-2 vs. greater than or equal to 3), type of resection (anatomic lobectomy vs. wedge resection), and nodule size (less than or equal to 3.0 cm vs. greater than 3.0 cm) were additional factors that were further evaluated to determine the effect of blood transfusions. Analyses stratified for each of these factors revealed that patients who received greater than or equal to 11 units of blood had a significantly decreased disease-free and overall survival compared with patients who received 3-10 units of blood. It is concluded that the amount of perioperative blood transfused is an independent prognostic factor that adversely effects disease-free and overall survival.

Adult↗
PubMed2005

A learning rule for the emergence of stable dynamics and timing in recurrent networks.

Neural dynamics within recurrent cortical networks is an important component of neural processing. However, the learning rules that allow networks composed of hundreds or thousands of recurrently connected neurons to develop stable dynamical states are poorly understood. Here I use a neural network model to examine the emergence of stable dynamical states within recurrent networks. I describe a learning rule that can account both for the development of stable dynamics and guide networks to states that have been observed experimentally, specifically, states that instantiate a sparse code for time. Across trials, each neuron fires during a specific time window; by connecting the neurons to a hypothetical set of output units, it is possible to generate arbitrary spatial-temporal output patterns. Intertrial jitter of the spike time of a given neuron increases as a direct function of the delay at which it fires. These results establish a learning rule by which cortical networks can potentially process temporal information in a self-organizing manner, in the absence of specialized timing mechanisms.

Action Potentials↗
PubMed2006

Stickiness in Hamiltonian systems: from sharply divided to hierarchical phase space.

We investigate the dynamics of chaotic trajectories in simple yet physically important Hamiltonian systems with nonhierarchical borders between regular and chaotic regions with positive measures. We show that the stickiness to the border of the regular regions in systems with such a sharply divided phase space occurs through one-parameter families of marginally unstable periodic orbits and is characterized by an exponent gamma=2 for the asymptotic power-law decay of the distribution of recurrence times. Generic perturbations lead to systems with hierarchical phase space, where the stickiness is apparently enhanced due to the presence of infinitely many regular islands and Cantori. In this case, we show that the distribution of recurrence times can be composed of a sum of exponentials or a sum of power laws, depending on the relative contribution of the primary and secondary structures of the hierarchy. Numerical verification of our main results are provided for area-preserving maps, mushroom billiards, and the newly defined magnetic mushroom billiards.

Journal Article↗
PubMedDate not supplied

Antiviral therapy using lamivudine and thymosin alpha1 for hepatocellular carcinoma coexisting with chronic hepatitis B infection.

BACKGROUND/AIMS: To observe the recurrence and prognosis of patients with hepatocellular carcinoma (HCC) coexisting with chronic hepatitis B infection with active virus replication after receiving antivirus therapy using lamivudine and thymosin alpha1 postoperatively. METHODOLOGY: From Jan. 2000 to Dec. 2002, 33 patients with HCC coexisting chronic hepatitis B infection with active virus replication were prospectively divided into two groups: control group (n= 17) received hepatectomy only, treatment group (n= 16) received hepatectomy and lamivudine plus thymosin alpha1 therapy postoperatively. The suppression of HBV-DNA, HBeAg seroconverted rate, recurrent tumor rate and the median survival for the two groups were observed and calculated. RESULTS: For the treatment group and control group, the one-year HBV-DNA suppression rate was 100% vs. 6% (p=0.0016); HBeAg seroconverted rate was 62.5% vs. 5.9% (p=0.0157); The median recurrent time was 7.0 vs. 5.0 months (p=0.0052); The median survival period was 10.0 vs. 7.0 months (p=0.10053), respectively. CONCLUSIONS: Antivirus therapy using lamivudine and thymosin alpha1 postoperatively may suppress the HBV reaction, delay the recurrent time and prolong the survival for HCC patients coexisting with chronic HBV infection with active virus replication.

Adjuvants, Immunologic↗
PubMed2004

Growth by random walker sampling and scaling of the dielectric breakdown model.

Random walkers absorbing on a boundary sample the harmonic measure linearly and independently: we discuss how the recurrence times between impacts enable nonlinear moments of the measure to be estimated. From this we derive a technique to simulate dielectric breakdown model growth, which is governed nonlinearly by the harmonic measure. For diffusion-limited aggregation, recurrence times are shown to be accurate and effective in probing the multifractal growth measure in its active region. For the dielectric breakdown model our technique grows large clusters efficiently and we are led to significantly revise earlier exponent estimates. Previous results by two conformal mapping techniques were less converged than expected, and in particular a recent theoretical suggestion of superuniversality is firmly refuted.

Journal Article↗
PubMed2006

Tissue Doppler imaging analysis at pre-cardioversion time predicts recurrent atrial fibrillation: a 12-month follow-up study.

INTRODUCTION: Tissue Doppler imaging (TDI) has been extensively used in several clinical settings. We aimed to investigate whether TDI can predict recurrent atrial fibrillation (AF). METHODS AND RESULTS: Seventy-four consecutive patients (aged 62.6 +/- 11.7 years) with AF (>48 hours and <6 months of duration) who underwent successful external electrical direct current cardioversion and 20 healthy individuals were enrolled. Conventional echocardiography and TDI were prospectively performed before cardioversion. Based on a cutoff point of 5.43 cm/sec for the negative systolic wave velocity (NSWV), derived by the normal controls (mean + 2 SD), patients were divided into Group I (36 patients) with a NSWV >5.43 cm/sec and Group II (38 patients) with NSWV 48 hours; all patients were in AF at 12 months. In Group II, all patients were in sinus rhythm at 12 months. However, those patients presenting with a NSWV less but near to 5 cm/sec had frequent episodes of asymptomatic paroxysmal AF lasting for <48 hours. CONCLUSION: One year after successful direct current cardioversion, TDI analysis at pre-cardioversion time may be a useful marker to identify a subgroup of patients with increased risk for AF recurrence.

Aged↗
PubMed1996

Cytomegalovirus retinitis in AIDS patients: influence of cytomegaloviral load on response to ganciclovir, time to recurrence and survival.

OBJECTIVES: Despite life-long maintenance therapy, cytomegalovirus (CMV) retinitis frequently progresses in patients with AIDS. Virological markers that could clarify pathogenesis and identify risk factors for progression are required. DESIGN AND METHODS: We prospectively recruited 45 patients with CMV retinitis. Blood and urine samples were collected before and after induction therapy, and on a monthly basis thereafter during routine medical and ophthalmological assessment, and at any time retinitis progressed. CMV load was measured by quantitative-competitive polymerase chain reaction (PCR). RESULTS: The median time to first progression of retinitis was 78 days and to death was 8.7 months. Eighty-five per cent of patients who were PCR-positive at diagnosis of retinitis became PCR-negative after 21 days of ganciclovir induction therapy. Six patients who remained PCR-positive after 21 days of treatment had a significantly higher CMV load at presentation (P = 0.005), and a shorter time to first progression of retinitis of 40 days. High CMV loads in blood at presentation were associated with a shorter time to progression (P = 0.16; relative hazard, 1.57) and a significantly shorter time to death (P = 0.004; relative hazard, 1.76). This significant relationship with survival remained after adjustment for potential confounding variables (CD4 count, age, method of drug administration). CONCLUSIONS: We conclude that CMV load in the blood of AIDS patients is an important factor in the pathogenesis of retinitis, and quantification of CMV could be used to both select patients for controlled clinical trials and to optimize individual anti-CMV induction therapy.

AIDS-Related Opportunistic Infections↗
PubMed1996

Long-term follow-up of endoscopically treated upper urinary tract transitional cell carcinoma.

OBJECTIVES: This report focuses on the long-term follow-up of patients with endoscopically treated upper tract transitional cell carcinoma (TCC) to determine the effectiveness of endoscopic therapy. METHODS: From May 1983 to April 1994, 44 patients with TCC of the upper urinary tract underwent conservative endourologic treatment with either electrocautery fulguration or neodymium:yttrium-aluminum-garnet laser at our institution. The mean follow-up period was 5 years (range, 3 months to 11 years). RESULTS: Renal pelvic tumor sizes ranged from 0.4 to 4.0 cm (mean, 1.5) and ureteral tumors from 0.2 to 1.0 cm (mean, 0.5). The majority of tumors were of pathologic grade 3 or less, and all were Stage T2 or less. Seventeen of 44 patients (38.6%) had local tumor recurrence (mean time to recurrence, 12.8 months; range 1.5 to 64). Mean recurrence time was 7.3 months for renal pelvic tumors and 17.8 months for ureteral tumors. Nineteen of 44 patients (43.2%) developed bladder tumors. The overall 5-year disease-free rate was 57%. No recurrent tumor was shown to have increased in grade, and one recurrent tumor was proved to have progressed in stage. Six patients (14%) ultimately required a nephroureterectomy for recurrence. There were no major complications as a result of endoscopic therapy. Six patients (14%) died of the effects of metastatic TCC, 5 of whom had known muscle invasive bladder TCC. CONCLUSIONS: Endourologic techniques and the conservative treatment of upper urinary tract TCC is an evolving field and can be safely and effectively used as a first-line treatment for upper tract TCC in selected patients.

Aged↗
PubMed2000

On-off intermittency at the onset of the ion-acoustic instability in a laboratory plasma

The ion-ion beam instability is experimentally studied just above threshold in a laboratory double-plasma device. Intermittent bursts of unstable waves are recorded in the target plasma and the distribution of the recurrence times of the bursts is estimated. At the onset of instability, the measurements are in agreement with the expected evolution deduced from a theoretical model that combines the normal form of a supercritical Hopf-Andronov bifurcation and the parametric noisy deviations from threshold typical of on-off intermittency. In both the experiment and the model, the distribution of the recurrence times of the bursts decays as an inverse power law and the evolution of the mean laminar length when the control parameter is increased beyond threshold exhibits a power law of exponent -1.

Journal Article↗
PubMed1979

Angina following myocardial revascularization. Does time of recurrence predict etiology and influence results of operation?

To assess the operative mortality and long-term results in patients undergoing repeat revascularization for recurrent angina, we analyzed 48 consecutive patients operated upon at New York University Medical Center between 1970 and 1978. Between January, 1970, and July, 1973, 15 patients underwent repeat revascularization with five operative deaths (33 percent). Thirty-three patients underwent similar operations from July, 1973, to July, 1978, with only one operative death (3 percent). Technical factors and improved methods of myocardial protection during the operation directly influence this decrease in operative mortality rate. The indication for reoperation was incapacitating angina developing within 2 months of the inital operation in 18 patients (early failures) and after more than 2 months in 30 patients (late failures). The early failures were most commonly attributed to technical factors (33 percent) and graft occlusion by exuberant pericardial scarring (33 percent). The late failures were commonly related to the development of new native coronary lesions (47 percent) and selection of an incorrect site for distal anastomoses (23 percent). The prognostic and therapeutic implications of these findings will be discussed in detail. Angina was abolished or significantly decreased in 90 percent of the survivors, and there were only two late deaths occuring 18 and 20 months postoperatively. These data indicate that patients undergoing repeat myocardial revascularization can be operated upon with low operative mortality rates and symptomatic improvement comparable to that of patients undergoing coronary artery bypass for the first time.

Adult↗
PubMed2004

Accelerated rates regression models for recurrent failure time data.

In this article, we formulate a semiparametric model for counting processes in which the effect of covariates is to transform the time scale for a baseline rate function. We assume an arbitrary dependence structure for the counting process and propose a class of estimating equations for the regression parameters. Asymptotic results for these estimators are derived. In addition, goodness of fit methods for assessing the adequacy of the accelerated rates model are proposed. The finite-sample behavior of the proposed methods is examined in simulation studies, and data from a chronic granulomatous disease study are used to illustrate the methodology.

Granulomatous Disease, Chronic↗
PubMed1999

Rizatriptan: a review of its efficacy in the management of migraine.

UNLABELLED: Rizatriptan is an orally active serotonin 5-HT1 receptor agonist selective for the 5-HT(1B/1D) subtypes. The efficacy of oral rizatriptan (5 or 10 mg) has been demonstrated in large (n = 309 to 1746) well designed comparative trials with placebo and oral sumatriptan. Two hours postdose, rizatriptan 5 or 10 mg was more effective than placebo at producing pain relief or a pain free status, relieving migraine-associated symptoms and normalising functional ability. In general, rizatriptan 10 mg appeared to be more effective than rizatriptan 5 mg. However, recurrence rates with rizatriptan 5 and 10 mg appeared to be similar to those with placebo. Patients were significantly more likely to achieve pain relief within 2 hours after receiving rizatriptan 5 mg than sumatriptan 25 mg and after rizatriptan 10 mg than sumatriptan 50 mg. This was also observed with rizatriptan 10 mg compared with sumatriptan 100 mg according to an age-adjusted and a prespecified per-protocol analysis. In general, rizatriptan was better than sumatriptan at relieving migraine-associated symptoms, particularly nausea, and in normalising functional ability depending on which doses were compared. The incidence of headache recurrence, time to onset of recurrence and the need for escape medication in nonresponders appeared to be similar between rizatriptan and sumatriptan. Over the 24 hours after the dose, rizatriptan 10 mg improved the quality of life of patients with migraine compared with placebo. Rizatriptan 10 mg also significantly improved work function compared with placebo and with sumatriptan 50 mg. Rizatriptan appears to be well tolerated with most adverse events being mild and transient. The most commonly experienced events included general digestive complaints, general neurological complaints, dizziness, somnolence, asthenia/fatigue and pain and pressure sensations. In clinical trials, the overall incidence of adverse events with rizatriptan 5 or 10 mg was similar to that with sumatriptan 25 or 50 mg but lower than that with sumatriptan 100 mg. Chest pain was reported by 1 to 3% of rizatriptan recipients and by 3 to 6% of patients receiving sumatriptan (25, 50 or 100 mg); clinically significant effects on ECG parameters, heart rate or blood pressure were not observed with rizatriptan. CONCLUSIONS: Rizatriptan produces pain relief and a pain free status, relieves associated symptoms of migraine, normalises functional ability and improves patient quality of life. Rizatriptan 10 mg appears to be more effective than rizatriptan 5 mg. In comparison with oral sumatriptan, rizatriptan may provide better relief from pain and nausea, with some evidence of a faster onset of action. Thus, rizatriptan 5 or 10 mg is likely to establish a place as an effective and well tolerated agent for the management of acute migraine.

Administration, Oral↗
PubMed1982

Urinary CEA for prediction of survival time and recurrence in bladder cancer.

The prognostic information from carcinoembryonic antigen was evaluated in bacteria-free urines of patients with bladder carcinoma. Patients with elevated (greater than or equal to 30 ng/ml) U-CEA had a poorer relative and symptom-free survival than patients with initial U-CEA below 30 ng/ml. Patients in whom U-CEA decreased from before to after radiation treatment had a better survival rate than patients with increasing U-CEA. These findings were most significant in cases with large (T3 + T4) tumors or with tumors of a lower differentiation (G3). U-CEA appeared to be an independent variable for prognostic evaluation of survival, since these differences were also true within the subgroups of known variables such as classes or grades. All but one of the patients, in whom short-term local control was obtained, had a posttreatment U-CEA below 50 ng/ml. In oncology units, where the more malignant bladder tumors are treated, U-CEA determinations may indicate which patients require intensified monitoring or treatment.

Adult↗
PubMed1983

So-called neuralgic amyotrophy: clinical features and long term follow-up.

The clinical features of 61 patients with Neuralgic Amyotrophy are analysed with special reference to recovery time, recurrence and residual deficits in 42 of these patients. Although the etiology is still unknown, N.A. has a characteristic clinical picture with a fairly typical pattern of symptoms and signs. A correct diagnosis is important because in spite of the severity and extent of the initial symptoms the overall prognosis in good.

Adolescent↗
PubMed2002

Estimating time to pregnancy from current durations in a cross-sectional sample.

A new design for estimating the distribution of time to pregnancy is proposed and investigated. The design is based on recording current durations in a cross-sectional sample of women, leading to statistical problems similar to estimating renewal time distributions from backward recurrence times. Non-parametric estimation is studied in some detail and a parametric approach is indicated. The results are illustrated on Monte Carlo simulations and on data from a recent European collaborative study. The role and applicability of this approach is discussed.

Journal Article↗
PubMed1996

Brain stem gliomas: therapeutic options at time of recurrence.

Despite contentions to the contrary, the majority of children with recurrent brain stem gliomas survive for at least 3 months after first relapse. Treatment can be undertaken and response determined, especially if brain stem necrosis is taken into consideration. Relatively few patients have been treated on well-designed studies accruing adequate numbers of patients. No conventional salvage therapy exists. Adequate studies with innovation approaches are needed to help individual patients, families and future generations of children with brain stem gliomas.

Antineoplastic Agents↗