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PubMed2004

Up-to-date long-term survival of cancer patients: an evaluation of period analysis on Swedish Cancer Registry data.

The natural development of cancers as well as the measures to fight the disease are often long processes that require decades of follow up. Available information on long-term survival will thus often appear outdated and irrelevant. A few years ago, period-survival analysis was proposed as a means to obtain more up-to-date information on long-term cancer survival. This article assesses period and conventional cohort-based survival analyses on their ability to predict future survival. Based on historical data from the nationwide Swedish Cancer Registry 5-, 10- and 15-year relative survival actually observed for patients diagnosed at one particular point in time are compared to the most recent period and cohort-based survival estimates available at that point in time. The study shows that period analysis can, in most cases, be used to provide more up-to-date long-term estimates of cancer survival. Period analysis reduces the time lag of the survival estimates by some 5-10 years for all cancers combined and especially affects the survival estimates for small intestine carcinoids, meningioma and intracranial neurinoma of the brain, non-seminoma testicular cancer, chronic lymphocytic leukaemia and Hodgkin's lymphoma.

Cohort Studies↗
PubMed1990

Periodicity analysis of sleep EEG in the second and minute ranges--example of application in different alpha activities in sleep.

To investigate the temporal organization of EEG sleep activity in the second and minute ranges we developed a method which, based on Fourier transformation, allows the presentation of periodic oscillations of spectral power and coherence. The application of this method is demonstrated in 3 subjects with different types of alpha activity during sleep: (a) alpha-sleep pattern (a physiological variant of NREM sleep activity); (b) abnormally increased arousal alpha activity. The results show that differences in the temporal organization of these alpha activities can be determined with the following parameters: period length, duration of sequences with periodic activity, number and rate of these sequences, and proportion of periodicities generated simultaneously in the left and right hemispheres. The physiologically modulated periodicities of the alpha-sleep pattern are contrary to a stereotyped 40-60 sec periodicity of abnormal arousal alpha activity. Such abnormal periodicity corresponds to periodicities occurring in association with other sleep disturbances, such as sleep apnea or periodic movements in sleep. Periodicity analysis gives additional criteria for a more refined evaluation of normal as well as abnormal sleep structure.

Adult↗
PubMed1977

Oscillating contractions in protoplasmic strands of Physarum: simultaneous tensiometry of longitudinal and radial rhythms, periodicity analysis and temperature dependence.

1. The construction of a 'twin-tension transducer' allows the simultaneous measurement of the same or different contraction rhythms at any selected sites of living plasmodia of Physarum polycephalum. This method has been used to analyse the relation of longitudinal and radial contraction activity within migrating plasmodia and plasmodial veins, under isometric as well as under isotonic conditions of measurement. 2. A periodicity analysis of the oscillating contraction rhythms revealed average period values for the longitudinal contraction cycle of 2-1 min and for the radial contraction cycle of 1-3 min at a temperature of 22 degrees C. 3. The periods of longitudinal contraction depend on the environment of the strands. The mean value under submerged conditions was 2-9 min. 4. The temperature dependences for both longitudinal and radial contraction cycles were determined to provide reliable values for the normal reaction range of the contractile system (cytoplasmic actomyosin). The values for radial contraction activity are 2-0 min at 16 degrees C, 1-5 min at 20 degrees C, and 1-2 min at 24 degrees C. The range between 16 degrees and 24 degrees C can be regarded as physiological. 5. The possibility is discussed that only one 'genuine' contraction frequency of cytoplasmic actomyosin exists in Physarum.

Cytoplasm↗
PubMed1984

Period analysis of the EEG in early putative Alzheimer's disease.

The EEG of patients with presumptive diagnoses of mild-to-moderate dementia of the Alzheimer type (DAT) and still residing in the community was examined using period analytic techniques. DAT patients were found to have significantly slower major and intermediate period EEG activity as compared to controls. Furthermore, one DAT patient, whose clinical EEG was read as normal, had period analytic EEG descriptors that were greater than one standard deviation below the mean of the control group. Results suggest that EEG activity, as quantified by period analysis, can be detected very early in the course of DAT.

Aged↗
PubMed1998

Alpha-periodicity analysis of small multidrug resistance (SMR) efflux transporters.

Proteins in the small multidrug resistance (SMR) family of transport proteins are about 110 amino acids in length and are predicted to have four transmembrane helices. This family is divided into a two groups, one of which we have referred to as small multidrug pumps (Smp) and confer resistance to a wide variety of quaternary ammonium compounds through a proton-drug efflux antiport mechanism. Members of the second group within this family have, as yet, not had their substrate profile characterized and are referred to as Sug proteins. Alpha-periodicity analysis was conducted on a set of six homologous proteins of the SMR family consisting of three established Smp and three Sug proteins. Several amino acid properties were used in the analysis including hydropathy, variability, and a substitution matrix for lipid exposed amino acids. The scanning window was varied between 8 and 14 residues and the alpha-periodicity was calculated from the peaks in the Fourier transform power spectra in the region between 3.0 and 4.3 residues/turn. This analysis adds to the hydropathy analysis to give a more confident prediction of which residues are within the lipid bilayer for each of the four transmembrane helices. Information was also obtained that allowed for the identification of zones within each transmembrane helix that face the interior of the helical bundle on one side and are lipid exposed on the other face.

Amino Acid Sequence↗
PubMed2004

Long-term survival rates of patients with prostate cancer in the prostate-specific antigen screening era: population-based estimates for the year 2000 by period analysis.

PURPOSE: In the era of widespread prostate specific antigen (PSA) screening, a large proportion of older men have to live with a diagnosis of prostate cancer. In this study, we applied a new method for up-to-date analysis of long-term survival to evaluate if and to what extent these patients still have any excess mortality compared to the general population. METHODS: Five- and 10-year absolute and relative survival rates for the year 2000 were derived from the 1973 to 2000 database of the Surveillance, Epidemiology and End Results Program using the recently introduced period analysis methodology. RESULTS: Overall, 5- and 10-year relative survival rates were approximately 99% and 95%; that is, excess mortality compared with the general population was as low as 1% and 5% within 5 and 10 years following diagnosis, respectively. Two-thirds of patients were diagnosed with well or moderately differentiated localized/regional prostate cancer, and among these patients, 5- and 10-year relative survival rates were above 100% (indicating the lack of any excess mortality) at all ages. CONCLUSION: While the value of PSA screening for lowering mortality due to prostate cancer remains to be shown by randomized clinical trials, the majority of patients diagnosed with prostate cancer in the PSA screening era do not have excess mortality compared to the general population under current patterns of medical care. This information may be important for both clinical management of, and for patients' coping with, the disease.

Aged↗
PubMedDate not supplied

Analysis of smoking behaviour among Iranian population: a cohort and period analysis.

BACKGROUND: The patterns of smoking in ageing cohorts are important to public health authorities. The aim of this study is to describe the patterns of smoking among Iranian population. METHODS: Data from cross-sectional surveys of Health and Disease Survey (HDS) in Iran were utilized. Smoking was categorized as no smoker, light smoker (less than 10 cigarettes a day), moderate smokers (10 to 20 cigarettes a day), and heavy smoker (more than 20 cigarettes a day). Age group cohorts were constructed by following each age group to the next age group in two consecutive surveys. The change in smoking behavior was express as the difference of smoking prevalence and 95% confidence interval around the difference were constructed. Three birth cohorts of 1930, 1960, and 1975 were constructed among smoker and their age at initiation of smoking were assessed for the three cohorts. RESULTS: Smoking was more prevalent among age group 25-39 in males and age group 40-60 in females. Smoking prevalence increased in all categories of smoking behavior among male cohort of 15-25 year age-group and stayed stable afterward up to their 40's. After age 40, the prevalence of smoking decreased in heavy smokers and stayed stable in light and moderate smokers. A different pattern was seen among female smokers. Age at initiation of smoking decreased in the last decades. Among the male birth cohort of 1930, just 32.6% of smokers started smoking before age 20 compared with 48.7% in birth cohort of 1975, P value < 0.0001. Similar pattern was seen among the female smokers. CONCLUSIONS: The pattern of smoking in Iranian population high lights the fact that smoking behavior is highly age dependent.

Adolescent↗
PubMedDate not supplied

Periodic analysis of ultradian (40 min less than tau less than 24h) respiratory variations in laboratory vertebrates of various circadian activities.

Continuous recordings of respiratory gas exchanges of various laboratory endotherm vertebrate species, which have either a nocturnal (mouse, rat) or diurnal (monkey, quail, chicken) or equivocal (guinea-pig) maximal activity, kept under controlled environmental conditions of temperature, humidity, ventilation and provided with food and water ad libitum, show ultradian oscillations of mean and low frequencies (1 less than f less than 35 c.day-1). Harmonic analysis was used to assess periodic or random ultradian variations and to compute amplitudes and phases of these oscillations when these vertebrates were submitted to a light (100 lx) and dark circadian alteration (LD 12:12). Spectral analysis shows that a 100-lx continuous illumination or continuous darkness decreases circadian respiratory rhythms and increases these ultradian respiratory oscillations.

Animals↗
PubMed1989

[Scientific articles in Ugeskrift for Laeger during a 25-year period. Analysis and interpretation of research results].

During a period of 25 years from 1959 to 1984, no essential alteration in the employment of descriptive statistics was observed in the original articles in the Ugeskrift whereas analytical statistics was employed to an increasing extent. In all of these volumes, defective, incorrect or less suitable employment of statistics could be demonstrated. Common problems were: analyses of materials in which some patients participated once while others participated on several occasions; debatable analyses of data on ranking scales; employment of 2-group tests on several groups; insufficient analysis of cross-over trials; lack of confidence intervals, and circular reasoning.

Denmark↗
PubMed1992

Digital period analysis of sleep EEG in depression.

The period-analyzed sleep electroencephalogram (EEG) was compared in a group of 9 depressed outpatients and 9 age-matched normal controls. Both groups showed rhythms in beta, delta, and theta activity with an approximately 90-min period. The phase and coherence between fast and slow frequency EEG measures, however, differed significantly in the two groups. Beta and delta rhythms were less coherent in the depressed outpatient sample. The control group showed higher coherence and a strong coupling of beta and delta activity. These preliminary data suggest that depression may be associated with some degree of ultradian rhythm disturbances though periodicity is unaffected.

Activity Cycles↗
PubMedDate not supplied

Reference period analysis of vaginal bleeding with triphasic oral contraceptive agents containing norethindrone or levonorgestrel: a comparison study.

The World Health Organization recommends the use of fixed reference periods for quantification of the incidence and severity of vaginal bleeding when patients use various forms of contraception. Ninety- and 110-day reference periods were used in the analysis of data from daily menstrual diaries kept by 72 healthy women in a one-year study of oral contraceptive agents containing ethinyl estradiol and either norethindrone or levonorgestrel. Analysis of bleeding patterns reported during both 90-day and 110-day periods revealed fewer days of bleeding and/or spotting overall with norethindrone than with levonorgestrel (e.g., a mean of 16.06 vs. 19.55 days, respectively, over the first 90-day period; P = .013) and significantly shorter bleeding and/or spotting episodes with the norethindrone preparation. This trend persisted when data were adjusted for a day-1 pill start. Using either method of analysis, duration of bleeding episodes was shorter among subjects taking norethindrone than levonorgestrel. Pills were missed in both study groups, but more women in the LNG/EE group missed from 1 to 3 pills in at least one cycle (31 vs. 21 in the NET/EE group). The between-group difference in bleeding events may be due to intrinsic hormonal differences in regimens or to the greater number of pills missed among levonorgestrel users.

Adult↗
PubMed2003

Sensitivity of human auditory evoked potentials to the harmonicity of complex tones: evidence for dissociated cortical processes of spectral and periodicity analysis.

A strong subjective tendency exists for simultaneous sound frequencies forming an harmonic series (integer multiples of the fundamental) to "group" together into a unified auditory percept whose pitch is similar to that of the fundamental. The aim of the study was to determine whether cortical auditory evoked potentials (AEPs) to complex tones differ according to whether the component frequencies of the stimuli are harmonically related or not. AEPs were recorded to continuous complex tones comprising four or more sinusoids. The vertex-maximal "change-potentials" (CP1, CN1, CP2), recorded to a stimulus cycle comprising one harmonic and five inharmonic complexes changing every second, showed no sensitivity to harmonicity, although an additional mismatch negativity was possibly present to the harmonic complex. In a second study the CP2 was significantly attenuated when an harmonic complex changed to a new one in the presence of an unchanging sinusoidal background tone, harmonically related to the first complex but not to the second, and thus becoming perceptually distinct. This, however, might be caused by lateral inhibitory effects not related to harmonicity. In a third experiment, when four concurrent sinusoidal tones came to rest on steady frequencies after a 5-s period of 16/s pseudo-random frequency changes, fronto-centrally maximal "mismatch-potentials" (MN1, MP2), were recorded. Both the MN1 and the MP2 were significantly shorter in latency when the steady frequencies formed an harmonic complex. Since the harmonic complex had a short overall periodicity, equal to that of the fundamental, while that of the inharmonic complex was much longer, the effect might be explained if the latencies of the mismatch-potential are related to periodicity. The perceptual grouping of harmonically related frequencies appears not to be a function of spectral domain analysis, reflected in the change-potentials, but of periodicity analysis, reflected in the mismatch-potentials

Acoustic Stimulation↗
PubMed2006

Class endogamy, inbreeding and migration during the Argentinean colonial period: analysis based on individuals of European ancestry.

During the Spanish colonial period, Córdoba was an important town due to its location suitable for controlling communication throughout a wide region of Argentina. As a typical colonial society, where individuals belonged to a well established social class, marriages among Whites were the result of strict norms and prejudices founded on nets of kinship, friendship and neighbouring. The objective of this paper is to determine, whether the elevated class endogamy among Whites during the colonial period resulted in high consanguinity and whether a process of selection of surnames was present in 1813. In both cases the interaction with the migratory flow was taken into account. It is concluded that (a) Although an endogamy of "class" existed among Whites, there is no evidence of the consequences on the biological structure of the population through preferential mating between relatives, as deduced from the low level of inbreeding from isonymy. (b) There was no differential reproduction reflecting the selection of families carrying certain surnames; therefore surnames followed a "neutral" model. (c) The diversity of surnames and the gene flow deduced from them were of a magnitude similar to present populations; this fact could have balanced the effect of the "class" endogamy. (d) Finally, the congruence between information derived from the population age distribution and historic data and the quantification of migration from surnames allowed the detection of mistakes in the census data file regarding the number of foreigners, thus validating the use of surnames as biological markers of the population structure.

Adolescent↗
PubMed2003

Chaotic and periodic analysis of fetal magnetocardiogram recordings in growth restriction.

OBJECTIVE: We studied how chaotic and periodic heart rate dynamics differ between normal fetuses (n = 19) and intrauterine growth restricted fetuses (n = 11) at 34 to 37 weeks of gestation. We quantified the chaotic dynamics of each heart rate time series obtained by fetal magnetocardiography (FMCG) using correlation dimension. METHODS: The FMCG was recorded digitally by a single-channel biomagnetometer in an electrically shielded room of low magnetic noise. The position of the fetal heart was determined using ultrasonography. RESULTS: The correlation dimension was significantly lower in IUGR than in normal fetuses (p < 0.001, t-test). The periodic dynamics were also obtained by FMCG and measured by power spectrum. The low-frequency components and therefore the periodicity of the low-frequency range were significantly higher in IUGR than in normal fetuses (p < 0.001, t-test). CONCLUSIONS: The analysis of FMCG recordings may offer important perspectives to understand significant features of the heart function of the fetuses. This technique improves the recognition of IUGR fetuses over healthy ones and may help improve perinatal morbidity and mortality.

Adult↗
PubMed1979

Microfilarial periodicity analysis of the survey data from six localities in Indonesia.

The survey data of microfilarial periodicity of 2 species of filariae Brugia malayi at 4 localities, Mahang and Lampihong in South Kalimantan, Bengkulu in South Sumatra, Palolo in Central Sulwesi, and the species of Brugia timori at 2 localities, Flores and Alor Islands in Nusa Tenggara were analysed by using Aikat and Das's modified statistical method. Nine cases at Mahang and five cases at Lampihong were recognized as same group of non-periodic B. malayi and 1 case at Mahang was considered to be nocturnal subperiodic B. malayi by their parameters estimated by the wave equation, the amplitude (a), the peak hour of microfilaria density (k) the periodicity index (D) and the test of equality for comparison of two series of data. The data of 9 cases from Bengkulu and 11 cases from Palolo were similarly analysed and recognized as the nocturnal periodic type of B. malayi. The data of 5 cases from Flores Island and 5 cases from Alor Island were also recognized as the nocturanal periodic type of B. timori. Thus, in these observations the non periodic strain of Brugia malayi was detected in South Kalimantan. Further studies on the principal vectors and their bionomics should be carried out.

Brugia↗
PubMed2005

A periodicity analysis of transmembrane helices.

Transmembrane helices and the helical bundles which they form are the major building blocks of membrane proteins. Since helices are characterized by a given periodicity, it is possible to search for patterns of traits which typify one side of the helix and not the other (e.g. amphipathic helices contain a polar and apolar sides). Using Fourier transformation we have analyzed solved membrane protein structures as well as sequences of membrane proteins from the Swiss-Prot database. The traits searched included aromaticity, volume and ionization. While a number of motifs were already recognized in the literature, many were not. One particular example involved helix VII of lactose permease which contains seven aromatic residues on six helical turns. Similarly six glycine residues in four consecutive helical turns were identified as forming a motif in the chloride channel. A tabulation of all the findings is presented as well as a possible rationalization of the function of the motif.

Algorithms↗