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PubMed2001

Study on early-onset benign occipital seizure susceptibility syndrome.

We prospectively studied the early-onset benign occipital seizure susceptibility syndrome to confirm the benign prognosis. The patients were 37 children followed for more than 2 years after meeting the following criteria on the first examination: (1) normal development before the onset of epilepsy, (2) onset between 1 and 8 years of age, (3) normal brain MRI and cranial CT findings, (4) partial seizures manifested both initial ictal vomiting and tonic eye-deviations, and (5) normal background activity with or without epileptic EEG foci regardless of location. The incidence and clinical characteristics of seizures, response to treatment, and EEG findings were analyzed. The total number of seizures ranged from one (n = 6) to 27 times, with a median of five times. Recurrent prolonged attacks resistant to antiepileptic drugs were recognized in 15 children, who had earlier onset of epilepsy and more frequent complications than the remaining 22 children. Interictal EEG revealed occipital foci in 26 children, 17 of whom later revealed a shift in predominant foci. At the final examinations, 28 patients had been seizure-free for at least 2 years. The clinical picture of this syndrome ranges from those with a few seizures to those with recurrent prolonged seizures initially resistant to antiepileptic drugs despite ultimate remission by 12 years of age.

Age Factors↗
PubMed2001

How to be a gray box: dynamic semi-physical modeling.

A general methodology for gray-box, or semi-physical, modeling is presented. This technique is intended to combine the best of two worlds: knowledge-based modeling, whereby mathematical equations are derived in order to describe a process, based on a physical (or chemical, biological, etc.) analysis, and black-box modeling, whereby a parameterized model is designed, whose parameters are estimated solely from measurements made on the process. The gray-box modeling technique is very valuable whenever a knowledge-based model exists, but is not fully satisfactory and cannot be improved by further analysis (or can only be improved at a very large computational cost). We describe the design methodology of a gray-box model, and illustrate it on a didactic example. We emphasize the importance of the choice of the discretization scheme used for transforming the differential equations of the knowledge-based model into a set of discrete-time recurrent equations. Finally, an application to a real, complex industrial process is presented.

Algorithms↗
PubMed1988

Serum CA 15-3 assay in the diagnosis and follow-up of breast cancer.

Serum CA 15-3 values were determined in 177 patients with primary breast cancer and in 41 with non-malignant breast disease. Increased preoperative serum CA 15-3 values (greater than 38 U ml-1) were observed in 7%, 17%, 64% and 67% of patients with stage I, II, III and IV disease, respectively and in none of the patients with benign breast disease. Patients with elevated serum CA 15-3 values had poor 3-year cumulative survival (27%). In the postoperative follow-up 9% of patients with no clinical evidence of disease, 33% with a single metastasis and 67% with two or more metastases had elevated values. Increasing or decreasing serum CA 15-3 values correlated with the clinical outcome in 26 out of 27 cases (96%), whereas serum values remaining in the reference range had no predictive value. At the time of recurrence elevated serum CA 15-3 values were also observed in patients with normal preoperative values. Increased serum CA 15-3 values preceded the clinical detection of tumour recurrence by up to 13 months. In conclusion, serum CA 15-3 levels had prognostic value in breast cancer, reflected the extent of clinically detectable disease and the presence of occult metastatic disease. Further research is warranted on the benefits of CA 15-3 assays in relation to adjuvant chemotherapy as well as the earlier detection and treatment of metastatic disease.

Antigens, Tumor-Associated, Carbohydrate↗
PubMed2001

Velocity measurement of particulate flow in microfluidic channels using single point confocal fluorescence detection.

This article presents a non-invasive, optical technique for measuring particulate flow within microfluidic channels. Confocal fluorescence detection is used to probe single fluorescently labeled microspheres (0.93 microm diameter) passing through a focused laser beam at a variety of flow rates (50 nL min(-1)-8 microL min(-1)). Simple statistical methods are subsequently used to investigate the resulting fluorescence bursts and generate velocity data for the flowing particles. Fluid manipulation is achieved by hydrodynamically pumping fluid through microchannels (150 microm wide and 50 microm deep) structured in a polydimethylsiloxane (PDMS) substrate. The mean fluorescence burst frequency is shown to be directly proportional to flow speed. Furthermore, the Poisson recurrence time and width of recovered autocorrelation curves is demonstrated to be inversely proportional to flow speed. The component-based confocal fluorescence detection system is simple and can be applied to a diversity of planar chip systems. In addition, velocity measurement only involves interrogation of the fluidic system at a single point along the flow stream, as opposed to more normal multiple-point measurements.

Microscopy, Confocal↗
PubMed1995

From Hamiltonian chaos to Maxwell's Demon.

The problem of the existence of Maxwell's Demon (MD) is formulated for systems with dynamical chaos. Property of stickiness of individual trajectories, anomalous distribution of the Poincare recurrence time, and anomalous (non-Gaussian) transport for a typical system with Hamiltonian chaos results in a possibility to design a situation equivalent to the MD operation. A numerical example demonstrates a possibility to set without expenditure of work a thermodynamically non-equilibrium state between two contacted domains of the phase space lasting for an arbitrarily long time. This result offers a new view of the Hamiltonian chaos and its role in the foundation of statistical mechanics. (c) 1995 American Institute of Physics.

Journal Article↗
PubMed2005

Stickiness in mushroom billiards.

We investigate the dynamical properties of chaotic trajectories in mushroom billiards. These billiards present a well-defined simple border between a single regular region and a single chaotic component. We find that the stickiness of chaotic trajectories near the border of the regular region occurs through an infinite number of marginally unstable periodic orbits. These orbits have zero measure, thus not affecting the ergodicity of the chaotic region. Notwithstanding, they govern the main dynamical properties of the system. In particular, we show that the marginally unstable periodic orbits explain the periodicity and the power-law behavior with exponent gamma=2 observed in the distribution of recurrence times.

Adhesiveness↗
PubMed2005

Spinal hydatid disease: a case series.

BACKGROUND: Over the past 10 years, 4 cases of spinal hydatid disease (3 men, 1 woman) were diagnosed and treated at our institution, with an average follow-up of 4 years. Hydatid disease of the spine is a rare condition with a poor prognosis that presents diagnostic and therapeutic challenges. METHODS: The patients were evaluated clinically, using the latest imaging modalities available in our institution. Decompressive surgeries were performed and the diagnosis was confirmed by histopathologic examination. All patients received long-term antihelminthic therapy with 400 mg of albendazole 3 times daily for 1 year. RESULTS: After surgery, all patients improved; however, over time, recurrence and residual disease were observed. Two patients had complete neurologic recovery at follow-up at 2 to 3 years, although there were radiographic signs of recurrence. The other 2 patients did not achieve complete neurologic recovery despite anterior decompression; they developed recurrent disease and the neurologic status deteriorated to spastic paraplegia. All patients refused further surgeries for recurrences and 2 patients died of complications of paraplegia. CONCLUSION: Diagnosis was challenging, eradication was difficult, and hydatid disease recurred in all 4 patients. In our experience, morbidity and mortality were high and prognosis was poor.

Adult↗
PubMed2002

Ferromagnetic self-regulating reheatable thermal rod implants for in situ tissue ablation.

BACKGROUND AND PURPOSE: Ferromagnetic compounds, when placed in a radiofrequency magnetic field, develop an electrical current. When placed in tissue, resistance to the transmission of the electrical current leads to heating of the tissues next to the ferromagnetic compound. The Curie temperature is a transition point at which the development of a particular temperature within the material results in loss of its magnetic properties; as such, when this temperature is reached, there is cessation of current, and thus heat production stops. Our goal was to examine the ablative impact of permanently implanted palladium and cobalt self-regulating temperature rods on solid abdominal and pelvic organs. These rods were designed to develop a maximum temperature of 70 degrees C. MATERIALS AND METHODS: In 16 pigs, renal, hepatic, uterine, and pancreatic ferromagnetic rods were placed using a template. The rods were delivered in 1-cm parallel rows of two rods each in order to ablate 7 g of tissue. The animals were subsequently treated in an extracorporeal magnetic field of 50 gauss rms at a frequency of 50 kHz. The position of the rods was confirmed by fluoroscopy before the animal was put in the magnetic field. The animals received one or two treatment sessions. Intralesional and extralesional temperatures were measured continuously. Serum chemistry was analyzed before surgery, after each treatment, and at the time of harvest. Two weeks following therapy, the treated tissues were harvested and examined histopathologically. RESULTS: In all tissues with properly aligned rods, the temperature of the tissue surrounding the rods exceeded 50 degrees C. Histologic review showed confluent tissue necrosis in 7 of 9 kidneys (78%), 6 of 9 livers (67%), 1 of 3 pancreases (33%), and 1 of 3 uterine specimens (33%). Necrosis extended for 2 mm beyond the periphery of the rods. All failures were secondary to technical misalignment of the rods, which occurred because of our attempt to treat more than one organ in each animal. CONCLUSIONS: Ferromagnetic rods, when properly aligned in a magnetic field, create well-defined areas of necrosis. There are no skip areas of viable tissue within the treated area, and there is a precipitous fall-off of injury just outside the area of treatment. Also, because the rods can be reactivated at any time, recurrent lesions within the same site can be treated. This form of minimally invasive in situ ablative therapy appears promising. Clinical trials in the kidney and in other abdominal and pelvic organs are pending.

Animals↗
PubMed2002

Chaotic and periodic motions of a cyclic bus induced by speedup.

We study the effect of speedup on the dynamical behavior of a single cyclic bus in a bus system with many bus stops. We present a nonlinear-map model of a cyclic bus to take into account the speedup. When the cyclic bus is delayed, the bus speeds up to retrieve the delay. It is found that the cyclic bus exhibits chaotic motion with increasing speedup. The chaotic motion depends on both speedup and the number of bus stops. Also, it is shown that the dynamical transition between the chaotic and periodic motions occurs with the increase of bus stops. The dependence of the recurrence time (one period) and Liapunov exponent on both speedup and the number of bus stops is calculated for distinct dynamic states. It is shown that the speedup has a significant effect on the bus motion. For a piecewise linear-map model, the cyclic bus does not exhibit the chaotic motion but a complex oscillatory motion with multiple periods occurs.

Journal Article↗
PubMed2004

Long-term clustering, scaling, and universality in the temporal occurrence of earthquakes.

Analyzing diverse seismic catalogs, we have determined that the probability densities of the earthquake recurrence times for different spatial areas and magnitude ranges can be described by a unique universal distribution if the time is rescaled with the rate of seismic occurrence, which therefore fully governs seismicity. The shape of the distribution shows the existence of clustering beyond the duration of aftershock bursts, and scaling reveals the self-similarity of the clustering structure in the space-time-magnitude domain. This holds from worldwide to local scales, for quite different tectonic environments and for all the magnitude ranges considered.

Journal Article↗
PubMed2006

Design and implementation of multipattern generators in analog VLSI.

In recent years, computational biologists have shown through simulation that small neural networks with fixed connectivity are capable of producing multiple output rhythms in response to transient inputs. It is believed that such networks may play a key role in certain biological behaviors such as dynamic gait control. In this paper, we present a novel method for designing continuous-time recurrent neural networks (CTRNNs) that contain multiple embedded limit cycles, and we show that it is possible to switch the networks between these embedded limit cycles with simple transient inputs. We also describe the design and testing of a fully integrated four-neuron CTRNN chip that is used to implement the neural network pattern generators. We provide two example multipattern generators and show that the measured waveforms from the chip agree well with numerical simulations.

Computers, Analog↗
PubMed1987

Factors predicting response of end stage squamous cell carcinoma of the head and neck to cisplatinum.

Cisplatinum significantly prolongs survival in end stage head and neck cancer but only 30-40% of patients respond. Many receive chemotherapy with little or no benefit and it would obviously be advantageous to determine in advance those patients likely to benefit. In 2 phase III trials of chemotherapy in end stage disease, 129 patients have been treated with cisplatinum, either alone or in 2-drug combination with bleomycin, methotrexate or 5-fluorouracil. Factors analysed in the entire group were age, sex, site, previous treatment, performance status and the use of cisplatinum in combination. A high albumen and oro- or nasopharyngeal site were significantly favourable, while a hypopharyngeal, middle ear, skin or paranasal site were all significantly unfavourable. In the separate analysis of the subgroup with recurrent disease, site of recurrence and time to recurrence were analysed in addition to the factors named above. Although similar trends to those in the entire group were observed none reached significant levels. In the subgroup with advanced previously untreated disease, histological grade was analysed in addition to the above factors. Good performance status emerged as significantly favourable. The emerging trends provide some insight regarding outcome but are not sufficiently clearcut to allow a decision to be made on who should and who should not be treated.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1995

Treatment of cutaneous angiosarcomas of the head and neck.

A total of six patients with cutaneous angiosarcomas involving the head and neck were treated during the period 1985-1994. The distribution of sites between the scalp and the rest of the head and neck was equal. Initial local treatment involved surgery for four patients and radiotherapy for two patients. In the surgical group, following seemingly adequate macroscopic surgical excision, all four patients had inadequate surgical margins on histology. Five of six patients had disease recurrence within the head and neck and of these a further three went on to have a second episode of recurrence. Median time to recurrence was 8 months. All cases were misdiagnosed clinically at initial presentation and three of six had initial inconclusive histology. Cutaneous angiosarcomas of the head and neck is an aggressive multicentric cancer. Radiotherapy offers the only real chance of obtaining adequate local control even if surgical excision is carried out. Radiotherapy must encompass wide fields and whole scalp irradiation is mandatory for scalp lesions. A combination of laterally opposed photon and electron fields provides a simple, quick and effective means to deliver a tumoricidal dose of 50 Gy to the whole scalp with minimal irradiation of the underlying brain.

Aged↗
PubMed1996

Clinicopathologic study on clear cell hepatocellular carcinoma.

In order to study the clinicopathologic characteristics of the clear cell variant of hepatocellular carcinoma (HCC), 215 consecutive cases measuring less than 5 cm in diameter were reviewed. The cases were divided into clear cell HCC (20 cases); focal clear cell HCC (77 cases); and non-clear cell HCC (118 cases). Clinical and pathological findings were compared among these groups. Clear cell HCC was moderately differentiated in 80% of cases and the incidence was not related to tumor size. The male to female ratio was 2.3:1, lower than the 6.9:1 of non-clear cell HCC. The association rate with liver cirrhosis was 90%, higher than the 59.3% of non-clear cell HCC. Three- and five-year survival rates, and no recurrence time were 54.5%, 33.3%, and 564 days, respectively, lower than the findings of 74.3%, 46.1%, and 770 days for non-clear cell HCC. But there is no significant difference in prognosis between both groups. Ultrastructurally, clear cells showed abundant glycogen storage and a variable degree of fat vacuoles, with a marked reduction of the number and size of organelles in the 8 cases examined. Non-clear cells of focal clear cell and non-clear cell HCC showed a moderate degree of glycogen storage in 85.7% and 28.6% of the seven cases examined from each group, with significant difference. It was concluded that clear cell HCC occurs mostly in the moderately differentiated form and is characterized by high female prevalence, high rate of association with liver cirrhosis, and has no significant difference in prognosis compared with non-clear cell HCC.

Adenocarcinoma, Clear Cell↗
PubMed1993

PCNA immunostaining in breast cancer.

Expression of proliferating cell nuclear antigen (PCNA) has been shown to be of prognostic value in patients with certain types of cancer. The aim of this study was to determine if the abundance of PCNA is inversely correlated with survival of patients with breast cancer. Paraffin blocks were available from 68 patients, all of whom had been followed clinically for at least 5 years. Sections from 20 patients showed no reactivity to PCNA and were excluded from the study because it was not possible to distinguish between true negatives and false negatives (those due to poor fixation of the original specimens). The PCNA index (the number of stained cancer cells as a percentage of the total number of cancer cells present) was calculated for the remaining 48 patients. Results were analysed by Wilcoxon's rank sum test (two tailed) and Pearson's correlation coefficient. There was no statistical difference between the PCNA indices of those patients dead from their disease within 5 years of diagnosis compared with those alive and without signs of breast cancer at 5 years. There was also no correlation between PCNA index and size of the cancer, involvement of axillary lymph nodes, time to recurrence or time to death. There was, however, a significant correlation between PCNA index and histological grade (P = 0.029). It appears that PCNA staining of stored paraffin sections is of little prognostic value in patients with breast cancer.

Antibodies, Monoclonal↗
PubMed1983

Cardiac involvement in juvenile rheumatoid arthritis. A follow-up study.

Cardiac involvement was diagnosed in 15 of 320 cases of JRA (4.7%) and was most frequent in children with active systemic disease. Ten children had pericarditis, 2 had myocarditis, 2 had peri-myocarditis and 1 had aortic valvulitis. The highest risk of heart involvement was found during the first three years but it could occur at any time. Recurrent episodes were seen in 60% of cases. The prognosis in pericarditis seems to be good since no patient developed cardiac tamponade or constrictive pericarditis and cardiac function evaluated by echocardiography was normal in all patients at follow-up. In patients with myocarditis and peri-myocarditis, a dilated left ventricle was found in 2 of 4 patients and 1 patient who died, had severe cardiac changes at autopsy. The prognosis in myocarditis thus seems to be worse. In valvulitis the prognosis depends on which valve is involved. The benefit of early treatment with corticosteroids is discussed.

Adolescent↗