Minimum follow-up time required for the estimation of statistical cure of cancer patients: verification using data from 42 cancer sites in the SEER database

BACKGROUND: The present commonly used five-year survival rates are not adequate to represent the statistical cure. In the present study, we established the minimum number of years required for follow-up to estimate statistical cure rate, by using a lognormal distribution of the survival time of those who died of their cancer. We introduced the term, threshold year, the follow-up time for patients dying from the specific cancer covers most of the survival data, leaving less than 2.25% uncovered. This is close enough to cure from that specific cancer. METHODS: Data from the Surveillance, Epidemiology and End Results (SEER) database were tested if the survival times of cancer patients who died of their disease followed the lognormal distribution using a minimum chi-square method. Patients diagnosed from 1973–1992 in the registries of Connecticut and Detroit were chosen so that a maximum of 27 years was allowed for follow-up to 1999. A total of 49 specific organ sites were tested. The parameters of those lognormal distributions were found for each cancer site. The cancer-specific survival rates at the threshold years were compared with the longest available Kaplan-Meier survival estimates. RESULTS: The characteristics of the cancer-specific survival times of cancer patients who died of their disease from 42 cancer sites out of 49 sites were verified to follow different lognormal distributions. The threshold years validated for statistical cure varied for different cancer sites, from 2.6 years for pancreas cancer to 25.2 years for cancer of salivary gland. At the threshold year, the statistical cure rates estimated for 40 cancer sites were found to match the actuarial long-term survival rates estimated by the Kaplan-Meier method within six percentage points. For two cancer sites: breast and thyroid, the threshold years were so long that the cancer-specific survival rates could yet not be obtained because the SEER data do not provide sufficiently long follow-up. CONCLUSION: The present study suggests a certain threshold year is required to wait before the statistical cure rate can be estimated for each cancer site. For some cancers, such as breast and thyroid, the 5- or 10-year survival rates inadequately reflect statistical cure rates, and highlight the need for long-term follow-up of these patients

On the Dynamics of the Spontaneous Activity in Neuronal Networks

Most neuronal networks, even in the absence of external stimuli, produce spontaneous bursts of spikes separated by periods of reduced activity. The origin and functional role of these neuronal events are still unclear. The present work shows that the spontaneous activity of two very different networks, intact leech ganglia and dissociated cultures of rat hippocampal neurons, share several features. Indeed, in both networks: i) the inter-spike intervals distribution of the spontaneous firing of single neurons is either regular or periodic or bursting, with the fraction of bursting neurons depending on the network activity; ii) bursts of spontaneous spikes have the same broad distributions of size and duration; iii) the degree of correlated activity increases with the bin width, and the power spectrum of the network firing rate has a 1/f behavior at low frequencies, indicating the existence of long-range temporal correlations; iv) the activity of excitatory synaptic pathways mediated by NMDA receptors is necessary for the onset of the long-range correlations and for the presence of large bursts; v) blockage of inhibitory synaptic pathways mediated by GABA(A) receptors causes instead an increase in the correlation among neurons and leads to a burst distribution composed only of very small and very large bursts. These results suggest that the spontaneous electrical activity in neuronal networks with different architectures and functions can have very similar properties and common dynamics

In silico Hierarchical Clustering of Neuronal Populations in the Rat Ventral Tegmental Area Based on Extracellular Electrophysiological Properties.

The ventral tegmental area (VTA) is a heterogeneous brain region, containing different neuronal populations. During recordings, electrophysiological characteristics are classically used to distinguish the different populations. However, the VTA is also considered as a region harboring neurons with heterogeneous properties. In the present study, we aimed to classify VTA neurons using approaches, in an attempt to determine if homogeneous populations could be extracted. Thus, we recorded 291 VTA neurons during extracellular recordings in anesthetized rats. Initially, 22 neurons with high firing rates (>10 Hz) and short-lasting action potentials (AP) were considered as a separate subpopulation, in light of previous studies. To segregate the remaining 269 neurons, presumably dopaminergic (DA), we performed analyses, using a combination of different electrophysiological parameters. These parameters included: (1) firing rate; (2) firing rate coefficient of variation (CV); (3) percentage of spikes in a burst; (4) AP duration; (5) Δt duration (i.e., time from initiation of depolarization until end of repolarization); and (6) presence of a notched AP waveform. Unsupervised hierarchical clustering revealed two neuronal populations that differed in their bursting activities. The largest population presented low bursting activities (17.5%). Within non-high-firing neurons, a large heterogeneity was noted concerning AP characteristics. In conclusion, this analysis based on conventional electrophysiological criteria clustered two subpopulations of putative DA VTA neurons that are distinguishable by their firing patterns (firing rates and bursting activities) but not their AP properties

Identification of powdery mildew resistance genes in common wheat (Triticum aestivum L). II. French cultivars

Major genes for resistance to the wheat powdery mildew pathogen, Erysiphe graminis f sp tritici, were analysed in 35 French wheat cultivars and in part in their parents. Cultivars were tested with a set of differential pathogen isolates which had specific interactions for each host line. The results were supplemented by cytological investigations and by consideration of pedigrees. Eighteen cultivars showed susceptible reactions. The remainder formed 9 groups with 1 or 2 resistance genes. Of the 5 known resistance genes present, Pm2 was the most common (in 5 cultivars), followed by Pm4b and Pm6 (each present in 4 cultivars), Pm5 (3 cultivars) and Pm8 (2 cultivars). In addition, an unknown resistance, tentatively designated Mlar, was identified in 3 cultivars.Identification des gènes de résistance à l'oïdium chez le blé tendre (Triticum aestivum L). II. Cultivars français. Des gènes majeurs de résistance à l'agent de l'oïdium du blé Erysiphe graminis f sp tritici ont été recherchés chez 35 cultivars français de blé, et quelques-uns de leurs parents. Les cultivars ont été testés avec un ensemble d'isolats différentiels présentant des interactions spécifiques sur chaque lignée hôte. Les résultats ont été complétés par des observations cytologiques et par une analyse des généalogies. Dix huit cultivars ont montré des réactions de sensibilité. Les autres forment 9 groupes possédant 1 ou 2 gènes de résistance. Des 5 gènes de résistance connus présents chez les cultivars étudiés, Pm2 apparaît le plus fréquemment (chez 5 cultivars) suivi de Pm4b et Pm6 (chacun présent chez 4 cultivars), Pm5 (3 cultivars) et Pm8 (2 cultivars). De plus, un gène de résistance inconnu a été identifié chez 3 cultivars, nommé provisoirement Mlar

Identification of powdery mildew resistance genes in common wheat (Triticum aestivum L). II. French cultivars

Major genes for resistance to the wheat powdery mildew pathogen, Erysiphe graminis f sp tritici, were analysed in 35 French wheat cultivars and in part in their parents. Cultivars were tested with a set of differential pathogen isolates which had specific interactions for each host line. The results were supplemented by cytological investigations and by consideration of pedigrees. Eighteen cultivars showed susceptible reactions. The remainder formed 9 groups with 1 or 2 resistance genes. Of the 5 known resistance genes present, Pm2 was the most common (in 5 cultivars), followed by Pm4b and Pm6 (each present in 4 cultivars), Pm5 (3 cultivars) and Pm8 (2 cultivars). In addition, an unknown resistance, tentatively designated Mlar, was identified in 3 cultivars.Identification des gènes de résistance à l'oïdium chez le blé tendre (Triticum aestivum L). II. Cultivars français. Des gènes majeurs de résistance à l'agent de l'oïdium du blé Erysiphe graminis f sp tritici ont été recherchés chez 35 cultivars français de blé, et quelques-uns de leurs parents. Les cultivars ont été testés avec un ensemble d'isolats différentiels présentant des interactions spécifiques sur chaque lignée hôte. Les résultats ont été complétés par des observations cytologiques et par une analyse des généalogies. Dix huit cultivars ont montré des réactions de sensibilité. Les autres forment 9 groupes possédant 1 ou 2 gènes de résistance. Des 5 gènes de résistance connus présents chez les cultivars étudiés, Pm2 apparaît le plus fréquemment (chez 5 cultivars) suivi de Pm4b et Pm6 (chacun présent chez 4 cultivars), Pm5 (3 cultivars) et Pm8 (2 cultivars). De plus, un gène de résistance inconnu a été identifié chez 3 cultivars, nommé provisoirement Mlar