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Published in Filomena Pereira-Maxwell, Medical Statistics, 2018
where O0 is the observed number of people with the event of interest in group 0 (for example, the unexposed or control group); E0 is the expected number of people with the event in group 0, under the hypothesis (null hypothesis) that the two groups being compared experience the same event hazard; O1 and E1 as above, for group 1 (for example, the exposed or treatment group). Observed and expected numbers in each group are calculated as a summation across all time strata or risk sets. The hazard ratio thus calculated is assumed to remain constant over time. An HR of 1 suggests the hazard or ‘risk' of the event is the same in the two groups. An HR greater than 1 suggests group 1 is more likely to experience the event. The opposite is true for an HR less than 1. See Box C.3 (Cox regression, p. 82) for an example and interpretation. The formula above is based on the same calculations as for the logrank or Cox-Mantel test. See also Mantel-Haenszel method (HRMH), Peto's method (HRPeto); ALTMAN (1991).
Biological Significance of Autologous Tumor Killing
Published in Ronald H. Goldfarb, Theresa L. Whiteside, Tumor Immunology and Cancer Therapy, 2020
Atsushi Uchida, Yoshitaka Kariya, Naoya Inoue, Norihiko Okamoto, Katsuji Sugie
The patients who had received curative surgery were retrospectively evaluated for the postoperative clinical course. Pathological examinations showed no tumor cells in the margins of tumor resections in all patients. No adjuvant anticancer therapy was performed after surgery. When local or distant recurrences developed, patients received chemotherapy, radiation therapy, or biological therapy. Clinical parameters assessed prospectively included age, sex. weight loss, other organ system diseases, and use of medications. Approximately 80% patients had performance status of 0, and 20% had performance status of 1, according to the ECOG performance status scale. The patients who are alive have had follow-up for 60 months. More than 80% of patients who were positive for ATK at the time of surgery remained tumor-free and were alive more than 5 years after the operation (Figure 1A,B). The other patients with ATK, however, developed metastases by 18 months and died by 37 months. In contrast, all patients without ATK activity relapsed within 18 months and died within 42 months. When the disease-free interval and total survival time were estimated by Kaplan-Meier analysis, the differences observed in curves for postoperative survival (disease-free interval and total survival) for patients with or without ATK activity were statistically highly significant according to the Cox-Mantel test (P < 0.00003) and the generalized Wilcoxon test (P < 0.00003). The correlation coefficient for ATK and postoperative clinical course was also high. The data strongly indicate that the potential of blood lymphocytes to kill autologous fresh tumor cells, tested at the time of surgery, may predict good prognosis of patients with primary localized tumors. The results also suggest that the measurement of ATK function at the time of surgery in cancer patients will provide valuable information for the probability of disease recurrence. Although all patients received curative surgery, only those with ATK ability are free from tumor and are alive after more than 5 years. Updated clinical data obtained indicate that none of the patients who have remained tumor-free for the observation period of 60 months develops recurrence and die after that period. No differences were observed in performance status, TNM classification, age or sex between groups that were positive for ATK activity and those that were negative, suggesting that the measurement of ATK activity may represent an independent prognostic parameter. All patients without ATK activity developed recurrences and died within 5 years, showing that a negative result in ATK tests indicates a poor prognosis. Our results suggest that ATK lymphocytes may be the main effectors in the immunological defense against growth and metastasis of tumor. The test, however, has no absolute prognostic value, since some patients with short disease-free interval and short total survival showed positive results. Since AMLTR and NK cell activity were also positive in these patients, the immunological control may not be operative for some types of cancer.
Evaluation of the genetic structure of Bromus inermis populations from chemically and radioactively polluted areas using microsatellite markers from closely related species
Published in International Journal of Radiation Biology, 2022
Elena V. Antonova, Marion S. Röder
The frequency of null alleles was estimated using the first algorithm of the Brookfield method (Brookfield 1996), as implemented in the MICRO-CHECKER package v. 2.2.3 (Van Oosterhout et al. 2004). The following parameters of genetical variability were used: allele frequency, observed (NA) and effective (NE) number of alleles per locus, the proportion of polymorphic loci, average observed heterozygosity (HO), the average expected heterozygosity (HE), and test of the genotype distribution by the Hardy–Weinberg ratio. Also, nonparametric (Mann–Whitney U-test, Wilcoxon matched pairs Z-test) and parametric (t-test) tests were used to compare the populations using the STATISTICA 10.0 software (StatSoft, Inc 2011). Since the HO and HE parameters were correlated with each other, the variables were considered to be dependent. Therefore, we used the t-test for dependent samples. Wright’s F-statistics coefficients were used to analyze the population structure. The Mantel test was used to assess the hypothesis of the effect of isolation by distance on genetic diversity. The level of statistical significance of the Mantel test was determined using 999 permutations. The calculation of these genetic parameters was carried out in the GenAlex 6.51b2 software package (Smouse et al. 2017). To visualize the obtained data, a dendrogram based on Nei’s standard genetic distance (Bias corrected) was drawn using the neighbor-joining method in POPTREE2 (Takezaki et al. 2010).
Dinucleotide (CA)n tandem repeats on the human X-chromosome and the history of the Mediterranean populations
Published in Annals of Human Biology, 2018
Josep Santamaría, Miguel M. Álvarez-Álvarez, M. Esther Esteban, Elies Ramon-Gurrea, Pedro Moral
Pairwise population relationships were estimated by the Δμ2 genetic distance index (Goldstein et al., 1995) through the MSA2 software and a Multidimensional Scaling plot was obtained using the program STATISTICA v 6.0. The population structure was approached using the analysis of the molecular variances of allele frequencies (AMOVA) through Fst statistics with the ARELQUIN program and it was also tested with the program STRUCTURE (Pritchard et al., 2000). Matrix correlation analysis was applied to check for correlations between different genetic and geographic distances by Mantel test and potential gene flow was assessed by the ADMIXTURE v. 2.0 software (Dupanloup & Bertorelle, 2001).