The cross product of interconnection networks

We study the cross product as a method for generating and analyzing interconnection network topologies for multiprocessor systems. Consider two interconnection graphs G₁ and G₂ each with some established properties such as symmetry, low degree and diameter, scalability, simple optimal routing, recursive structure (partitionability), fault tolerance, existence of node-disjoint paths, low cost embedding, and efficient broadcasting. We investigate and evaluate the corresponding properties for the cross product of G₁ and G₂ based on the properties of G₁ and those of G₂. We also give a mathematical characterization of product families of graphs which are closed under the cross product operation. This investigation is useful in two ways. On one hand, it gives a new tool for further studying some of the known interconnection topologies, such as the hypercube and the mesh, which can be defined using the cross product operation. On the other hand, it can be used in defining and evaluating new interconnection graphs using the cross product operation on known topologies     

Single-dose versus multiple instillations of epirubicin as prophylaxis for recurrence after transurethral resection of pTa and pT1 transitional-cell bladder tumours: a prospective, randomized controlled study

OBJECTIVE: To compare single-dose and multiple instillations of epirubicin in the chemoprophylaxis of superficial bladder tumours. PATIENTS AND METHODS: In a prospective randomized and controlled study, 168 evaluable patients were assigned to three groups after transurethral resection of bladder tumour (TURBT) and histological confirmation of its superficial nature (pTa and pT1). The groups were comparable for tumour stage, grade and other tumour characteristics. In group 1, patients received a single dose of 50 mg epirubicin in 50 mL normal saline immediately after TURBT; group 2 received 50 mg epirubicin in 50 mL normal saline 1-2 weeks after TURBT and the instillations were repeated for 8 weeks and thereafter monthly to complete one year of treatment: group 3 (control group) received no adjuvant therapy after TURBT. The patients were assessed by cysto-urethroscopy, urine cytology and DNA flow cytometry 8 weeks after resection and then every 3 months during the first 2 years and 6 monthly thereafter during the next 2 years. Intravenous urography was performed annually and when otherwise indicated. RESULTS: The recurrence rate was significantly lower in the patients treated with epirubicin than in the control group (24, 25 and 52%, respectively; P < 0.001). In those receiving epirubicin, the rates of recurrence were statistically comparable (P = 0.9). Patients who had a large tumour burden showed slightly lower recurrence rates with single-dose epirubicin than with delayed maintenance therapy but the difference was statistically insignificant. Patients with a history of bladder tumours before treatment had lower recurrence rates with maintenance treatment than with a single dose (34.6 and 22.6% in groups 1 and 2, respectively); again this difference was statistically insignificant. Patients with grade 3 tumours showed a marginal difference in favour of maintenance therapy. The rates of progression amongst the three groups were 5.5, 3.4 and 9.3%, respectively, with no significant differences. The overall toxicity rates were comparable in the two treated groups (22 and 25%). CONCLUSION: With the possible exception of grade 3 tumours, single-dose immediate epirubicin is as effective as delayed maintenance therapy, with the advantage of being more cost-effective.     

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PURPOSE: To compare the response rates, toxicities and survival durations of elderly patients (70 years of age or more) with those of younger patients (less than 70 years of age) with non-small-cell lung cancer (NSCLC) treated with cisplatin-based chemotherapy. PATIENTS AND METHODS: We analyzed retrospectively the data of 203 assessable patients entered on a prospective randomized trial of cisplatin-based combination chemotherapy. Chemotherapy consisted of three dosage regimens: (1) vindesine and cisplatin (VP); (2) mitomycin, vindesine and cisplatin (MVP); or (3) etoposide and cisplatin alternating with vindesine and mitomycin (EP/VM). RESULTS: A greater proportion of elderly patients had localized disease and more squamous cell carcinoma than non-elderly patients. The overall response rates were 44% in the elderly group and 28% in the non-elderly group. In the EP/VM arm, the response rate was significantly better in the elderly group than in the non-elderly group. The frequency of grade 4 leukocytopenia in the MVP and EP/VM arms in the elderly group was significantly greater than in the non-elderly group (P < 0.05). No differences were found in nonhematological toxicities between the two groups. There was no difference in overall survival between the groups. CONCLUSION: Elderly patients treated with mitomycin-containing regimens have higher hematologic toxicities than younger patients. The results of this study are consistent with the previously reported pharmacologic data on mitomycin suggesting altered pharmacokinetics in elderly patients. The improved response rate in the elderly patients was probably because more elderly patients had earlier disease, squamous cell carcinoma and better performance status. Cisplatin-based chemotherapy was tolerable for most elderly NSCLC patients with good performance status.     

Comparisons of pulmonary and sinonasal lesions in patients with cystic fibrosis. Evaluation using computerized tomography

INTRODUCTION: Cystic fibrosis is a recessive genetic systemic exocrinopathy caused by a variety of mutations in the cystic fibrosis transmembrane conductance regulator gene (CFTR). The disease is characterized by alterations of the secretions, which become thickened and viscous. Both the paranasal sinuses and the lung parenchyma are involved in all cases. The aim of this study was to assess a correlation between the rhinosinusal and lung parenchyma changes in cystic fibrosis patients. MATERIAL AND METHODS: Eighteen patients (11 men and 7 women, age range: 8 to 22 years) were examined with chest HRCT and sinonasal low dose CT. Lung symptoms were found in all patients; 13 of them, also affected with rhinosinusal symptoms, had been examined with ENT and nasal endoscopy. The other 5 patients, without rhinosinusal symptoms and previously examined with ENT, were evaluated as control group. Chest CT was performed with the high-resolution technique, 2 mm slice thickness and 10 mm table feed. Rhinosinusal CT was performed with the low dose technique, acquiring contiguous 2-4 mm thickness coronal sections. The CT patterns were analyzed by two radiologists and scored as slight, medium and diffuse involvement of both districts. RESULTS: No statistically significant correlation between lung and sinonasal damage was found in our study. Parenchymal lung involvement appeared more severe than sinonasal involvement in 14/18 patients. The retention of secretions in the paranasal sinuses, even if limited, was demonstrated in all symptomatic and asymptomatic patients. CONCLUSIONS: The absence of correlation between pulmonary and sinonasal damage and more generally, the different severity of cystic fibrosis can be caused by different allele mutations of the cystic fibrosis transmembrane conductance regulator gene, the most frequent of which is Delta F-508.     

DMD-specific FISH probes are diagnostically useful in the detection of female carriers of DMD gene deletions

The challenge of Duchenne muscular dystrophy (DMD) carrier identification resides in the ability to identify the presence of a mutant gene over the background contributed by the normal allele. Current diagnosis of carrier status when a deletion has been identified in a proband is based on an analysis of a gene dosage. We present a diagnostic strategy that uses fluorescence in situ hybridization (FISH) to detect female carriers with major deletions in the dystrophin gene. We screened a human X-chromosome-derived genomic library with a full-length dystrophin cDNA and isolated 15 dystrophin-specific cosmids that contain DMD gene exons. Six cosmids were further tested as FISH probes in control individuals and subsequently applied on chromosomes from eight males with DMD and known deletions and on samples from three female carriers. As expected, X chromosomes in normal females displayed four signals, two for the DMD-specific probe and two for the X-chromosome centromeric probe. Hybridization on chromosomal spreads from carriers of deletions revealed only one signal from the DMD-specific probe and two from the control centromeric probe. Males carrying deletions showed no DMD-specific signal for the deleted exons tested. Our data indicate that FISH could represent an alternative method for the detection of female carriers with DMD gene deletions.     

Selective phosphorylation of adult tau isoforms in mature hippocampal neurons exposed to fibrillar A beta

How senile plaques and neurofibrillary tangles are linked represents a major gap in our understanding of the pathophysiology of Alzheimer's disease. We characterized a hippocampal neuronal culture system in which tau undergoes maturation in vivo; rat neurons maintained in culture for more than 3 weeks replicated the splicing and phosphorylation changes that tau undergoes upon maturation in situ. Using this model system, we induced an Alzheimer-like neuritic dystrophy following the application of fibrillar beta-amyloid. The dystrophy consisted of focal distortions and swellings within the neurites and an altered phosphorylation of the adult tau isoforms. Fibrillar beta-amyloid induced the concomitant activation of MAP kinase and GSK3 beta. The aberrant activation of several signaling pathways may lead to the abnormal phosphorylation of tau and neuritic degeneration.     

The inactivated plasmid inititator protein RepC/RepC* may have a regulatory role

During replication of the plasmid pT181, the initiator protein RepC is modified by the addition of an oligodeoxynucleotide, giving rise to a new form, RepC*. Here we show that during in vitro replication, RepC* is radioactively labeled, suggesting that the source of the RepC* oligodeoxynucleotide is the newly synthesized pT181 DNA. The RepC/RepC* heterodimer retains its ability to bind the pT181 double-strand origin and, therefore, it may act as a competitive inhibitor of the RepC homodimer during replication.     

Semi-Markov models with an application to power-plant reliabilityanalysis

Systems with, (1) a finite number of states, and (2) random holding times in each state, are often modeled using semi-Markov processes. For general holding-time distributions, closed formulas for transition probabilities and average availability are usually not available. Recursion procedures are derived to approximate these quantities for arbitrarily distributed holding-times; these recursion procedures are then used to fit the semi-Markov model with Weibull distributed holding-times to actual power-plant operating data. The results are compared to the more familiar Markov models; the semi-Markov model using Weibull holding-times fits the data remarkably well. In particular comparing the transition probabilities shows that the probability of the system being in the state of refitting converges more quickly to its limiting value as compared to convergence in the Markov model. This could be because the distribution of the holding-times in this state is rather unlike the exponential distribution. The more flexible semi-Markov model with Weibull holding-times describes more accurately the operating characteristics of power-plants, and produces a better fit to the actual operating data     

Source separation using a criterion based on second-orderstatistics

It is often assumed that blind separation of dynamically mixed sources cannot be done with second-order statistics. It is shown that separation of dynamically mixed sources indeed can be performed using second-order statistics only. A criterion based on second-order statistics for the purpose of separating crosswise mixtures is stated. The criterion is used in order to derive a gradient-based separation algorithm, as well as a Newton-type separation algorithm. The uniqueness of the solution representing the separation is also investigated. This reveals that (1) the channel system is parameter identifiable under weak conditions, and (2) if the sources have the same color, there exists at most two solutions. The local convergence behavior of the proposed algorithm is studied and reveals a sufficient condition for local convergence. Furthermore, the estimates of the channel system are shown to be consistent or to locally minimize the criterion