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PubMed1987

Occurrence of Phyllodistomum umblae (Fabricius, 1780) in the ureters of coregonids of Lake Yli-Kitka in northeastern Finland.

380 whitefish (Coregonus sp.) and 260 vendace (Coregonus albula L.) were studied from Lake Yli-Kitka in northeastern Finland during 1980-1982. 33% of the whitefish and 38.5% of the vendace were infected with Phyllodistomum umblae (Fabricius, 1780), the average intensity of infection being 4.2 and 2.3 per infected fish, respectively. No clear seasonality was observed in either the prevalence and intensity of infection or in the level of maturation and the length of P. umblae in both fish species, which points to a continuous invasion and maturation of these trematodes. The prevalence and intensity of P. umblae infection was highest in the middle-sized whitefish. Similar results were obtained when the mean number of worms per fish and the level of overdispersion (S2/x) are plotted against the length of the fish. With regard to vendace the prevalence and intensity of infection per infected fish and per fish studied increased as the fish length increased: only the variance-to-mean ratio remained constantly low. Overdispersion indices (S2/x) revealed that in the whitefish P. umblae is more overdispersed than in vendace when studied using data from seasonal periods with size-groups as homogenously infected as possible. The negative binomial distribution gave a good fit in the case of vendace and with one exception also for whitefish, and the values of parameter k are well within the limits most often found in parasitological studies.

Animals↗
PubMed1987

A Markov model for a clinical episode of recurrent genital herpes.

A time-homogeneous Markov process is proposed for modeling the clinical course of recurrent genital herpes and is used to obtain estimators for various characteristics of the disease episode. The model has a finite, discrete time parameter and discrete state space, with six transient states corresponding to the six stages a herpes lesion may enter. The healed condition is represented as an absorbing state. The number of lesions present at the onset of the clinical episode and the number of lesions appearing during the course of the episode are assumed to have negative binomial distributions. Clinical trial data are used to examine the assumptions of the model and to estimate its parameters. Estimates of clinical variables based on the model are computed and are compared with those calculated directly to assess how well the model represents the biological process of the disease.

Herpes Genitalis↗
PubMed1986

Internal regulatory systems--common consistent patterns in the parasite-host relationships with specific parasites.

While studying the population ecology of cattle warble flies (Diptera, Hypodermatidae) in Czechoslovakia, the Soviet Union and Mongolia a firm internal regulatory system, determining the population density of parasites and operating on the principle of negative feedback, was demonstrated. The negative binomial distribution proved to be a suitable model in other parasite groups as well. The internal regulatory systems are common consistent patterns in the parasite-host relationship with specific parasites. These consistent patterns and the methodical approach to them are of wider importance not only for parasitology in particular, but for the research of ecosystems in general. This trend of research can be therefore considered to be momentous, comparable with other concepts in parasitology.

Animals↗
PubMed1986

The impact of litter effects on dose-response modeling in teratology.

The fitting of dose-response models to teratology data involving littermates in order to generate estimates of teratogenic risk is receiving increasing attention as a potential alternative to the "safety-factor" approach to risk estimation. In this paper, we utilize the beta-binomial distribution to introduce varying degrees of intralitter correlation, and, for purposes of illustration, consider a logistic dose-response model that describes the logit of risk as a straight-line function of ln(dose). The biases and (exact and asymptotic) variances of the maximum likelihood estimators of the intercept and slope are studied by simulation as a function of the intralitter correlation structure.

Animals↗
PubMed1985

Spatial dispersion of spindle cells in the human thoracic aorta.

The intima of the human thoracic aorta thickens with age. Those portions of thickened intima that lack foci of atheronecrosis or foam cells are populated by smooth muscle cells, which are usually characterized in sections by spindle-shaped nuclei, and by occasional superficial monocytic macrophagic cells. Populations of these cells were censused by counting nuclear profiles at 40 anatomically defined sites in each of 200 aortas aged 10 to 69 years. The different depths within the intima between the lumenal surface and the media with minor exceptions did not significantly differ in cell numbers. The density of cells decreased with thickness at all ages and with age at all thicknesses after completion of growth and maturation. The total numbers of cells in 100-microns lengths of intima, assessed in longitudinal tissue sections, were virtually constant with aging after 20 to 29 years. The dispersion of cells over the intima in the lateral walls of the thoracic aorta followed a negative binomial distribution, which has an upward skewed unimodal form. Because of the sampling properties of this form of distribution the mean of eight to 12 measurements appears to be adequate to describe the spindle cell numbers in the nonnecrotic parts of an aorta.

Adolescent↗
PubMedDate not supplied

[Normal values of T3-index and of thyroxine (T4) (author's transl)].

The normal values of T3-index and of thyroxine (T4) have been evaluated comparing a binomial distribution to frequential curve of all the values obtained. The findings are: T3-index = 89 divided by 112; T4 = 3.7 divided by 15.3 microgram/100 cm3 of serum.

Humans↗
PubMed1979

[Falsely positive values in multi-channel analysis: an estimation of their frequency with Sylvester's formula and their reduction by a multivariate test quantity (author's transl)].

The application of the binomial distribution for determining the number of "falsely positive values" is not suitable because of the partly strong correlations between the clinical chemical parameters. We have therefore tried to obtain more precise estimations for the number of falsely positive values by using a generalisation from Sylvester's formula and taking into account the correlations. We use multivariate statistics for testing a patient's value" when several laboratory parameters are simultaneously considered. The multivariate technique leads firstly to a significant reduction of the erroneously interpreted "falsely positive values" and secondly allows the detection of hidden implausible constellations of values.

Autoanalysis↗
PubMed1983

Enzyme analysis of lymphoproliferative diseases: a useful addition to cell surface phenotyping.

Lymphocytes from patients with acute and chronic T-cell malignancy or chronic T gamma lymphocytosis were characterized by studying the activity of three enzymes involved in purine metabolism and by determining the isoenzyme pattern of lactate dehydrogenase (LDH) in addition to analysis of surface marker expression with monoclonal antibodies. Four clinically different types of disease were distinguished on the basis of the enzyme parameters. Lymphocytes from patients with acute lymphocytic leukemia (T-ALL) showed an enzyme profile similar to that of normal thymocytes, i.e., an elevated level of adenosine deaminase (ADA) activity as compared with normal T lymphocytes, reduced activities of purine 5'nucleotidase (5'NT) and purine nucleoside phosphorylase (PNP), and a binomial distribution of the LDH isoenzyme pattern. Cells from "null"-ALL patients had an ADA/PNP ratio that was intermediate between that of normal T cells and that of T-ALL cells or thymocytes, but their 5'NT activity and LDH isoenzyme pattern were thymocyte-like. Patients with chronic T-cell proliferation were subdivided into those with chronic T gamma lymphocytosis and those with proven chronic T malignancy. The lymphocytes from these patients had ADA and PNP activities within the ranges of those of normal T lymphocytes. However, the ADA activity and/or the ADA/PNP ratio were consistently higher in the cells from the patients with chronic T gamma lymphocytosis than in those with chronic T malignancy. The enzyme profile of the cells from the T gamma patients was similar to that of T gamma cells of normal individuals. The cells from patients with chronic T malignancies showed a heterogeneous enzyme pattern as compared with that of normal T lymphocytes. Analysis with monoclonal antibodies enabled us to distinguish null-ALL patients from the other leukemias studied, but a distinction between chronic and acute T-cell proliferation disease, for instance, was not possible with monoclonal antibodies alone. Our data demonstrate that the enzyme profiles studied provide supplementary information for classification and diagnosis of lymphoproliferative diseases to that obtained with cell surface markers alone.

5'-Nucleotidase↗
PubMed1983

Mutations at more than one locus may be involved in cystic fibrosis--evidence based on first-cousin data and direct counting of cases.

Cystic fibrosis was present in 35 of 5,265 first cousins of index cases with the disease. The gene frequency was estimated to be .0281 +/- .00544, using an improved method that allows for the influence of cousin sibship size upon the estimate. This figure is higher than that obtained by direct counting of cases in Victoria, Australia, from 1955-1979 (.0198 +/- .000127), raising the possibility that multiple gene loci may be involved in this disease. Further analysis showed that the number of affected first cousins fitted very well with an expected number based on a model involving two gene loci, each responsible for half the cases of cystic fibrosis. Agreement with expectations based on a single locus was not good. An alternate explanation of gross underascertainment of cases is dismissed because the index sibships were shown to fit very closely a truncate binomial distribution. The gene frequencies at the putative two loci would then each be .0140 and heterozygote frequencies one in 36. One in 18 people would be heterozygous at either one or the other of the loci.

Adult↗
PubMed1984

Multivariate methods in ophthalmology with application to other paired-data situations.

Methods are presented for performing multiple regression analyses and multiple logistic regression analyses on ophthalmologic data with normally and binomially distributed outcome variables, while accounting for the intraclass correlation between eyes. These methods are extended to more general nested data structures where a variable number of subunits are available for each primary unit of analysis, as in familial data. These methods can also be applied to other types of paired data, as in matched studies with a variable matching ratio, where one has a continuous outcome variable and wishes to control for other confounding variables while maintaining the matching. Examples are given of these methods with a group of over 400 patients with retinitis pigmentosa, in which spherical refractive error and visual acuity are related to genetic type after the effects of age, sex and the presence of cataract, have been controlled.

Biometry↗
PubMed1984

A two-year survey of mucocutaneous lymph node syndrome in northeastern Italy. Epidemiological and clinical findings.

A two-year retrospective survey of cases of mucocutaneous lymph node syndrome (MLNS, Kawasaki disease) was conducted by a collaborative research group in Northeastern Italy (Friuli Venezia-Giulia) by reviewing the records of all patients admitted in the paediatric wards of this area from January 1, 1981 to December 31, 1982. 19 cases of MLNS were identified representing an overall incidence in the two-year period of 14.7 cases per 100,000 children younger than 5 years of age. Seasonal clustering of cases was observed, 17 out of 19 cases occurring either in spring or autumn (P = 0.0004, binomial distribution) and 11 out of 19 cases occurring in spring alone (P = 0.0023). No evidence for direct contact between cases or common source exposure emerged, and no risk factors were identified. The clinical spectrum of the disease was similar to that described elsewhere, carditis, uveitis, arthritis and urethritis being the most frequent complications. One infant died, and in this case coronary artery aneurysms were demonstrated by two-dimensional echocardiography. In the remaining cases recovery was complete without sequelae. This study suggests that MLNS is more frequent than expected and that the real incidence of the disease is probably underestimated. The evidence of seasonal clustering of cases strongly suggests the presence of a yet unidentified exogenous factor playing a role in the etiology of the disease.

Child↗
PubMed1984

Some aspects of methodology in speech audiometry.

The aim of this study was to provide more knowledge about the influence of various factors on the reliability of speech audiometric measurements. On the basis of these data, new material on speech has also been developed for measurements of the speech reception threshold in noise. In a theoretical and a clinical investigation it has been shown that the reliability of speech discrimination scores may be predicted by using the binomial distribution. The reliability mainly depends on the score obtained and on the length of the word list. Curves with confidence intervals as well as diagrams which indicate when two different discrimination results deviate significantly from each other are presented. On the whole, the reliability is surprisingly poor. The reliability of speech reception threshold (SRT) measurements was studied by computer simulations and clinical studies. The SRT results of "subjects" who had poor speech discrimination were unreliable and were greatly affected by the level at which the test started. Some new methods were also simulated, one of which (the 2x4-word method) was 8% faster and also somewhat more reliable in the clinical studies than the ordinary 10-word method. It was also less affected by the patient's speech discrimination. Several speech lists with exactly the same content of sound, but with new sentences, were obtained by editing a list of ten spoken Swedish sentences in a computer. A noise was synthesized from the speech material by the computer to obtain the exact same spectrum of the speech and the noise. This material was tested monaurally on normal-hearing subjects and hearing-impaired subjects. A very steep intelligibility curve was obtained in noise (25%/dB), which gave a standard deviation of only 0.44 dB at repeated threshold measurements in noise for the normal-hearing subjects when the learning effect was outbalanced. This figure increased to 1.1 dB for those with severely impaired hearing. The learning effect between the first and the second thresholds did not exceed 1 dB. The threshold values ranged from -8 to -5 dB signal-to-noise ratio for those with normal hearing and from -7 to +7 dB for those with impaired hearing. The new sentence and noise material developed is well suited for clinical measurements of the speech reception threshold in noise.

Adult↗
PubMed1983

[Dose as the determining factor for the size of the parasite population in the Muellerius capillaris/Cernuella cespitum arigonis system (Nematoda, Protostrongylidae/Mollusca, Stylommatophora].

Ten lots, each one made up of 40 specimens of the snail Cernuella (Xeromagna) cespitum arigonis, were infected with L1 of the nematode Muellerius capillaris, at dosages ranging from 50 up to 1,000 L1/mollusc, in order to determine the influence of the infecting dose on the invasion and further development of the parasite population. Mathematical calculations are based on a basic model of a growing population. During the invasion phase a densith dependence on the number of available larvae was demonstrated, the process being adjusted to a binomial distribution and, secondly, to a Poisson type. The step from L1 to L2 was also density-dependent, and also the development from L2 to L3.

Animals↗
PubMed1983

Tables for the cytogenetic study of fragile X chromosomes for diagnostic purposes.

The frequency of expression of the fragile X chromosome varies from patient to patient. Many cases have been reported showing frequencies of less than 2%. With such low frequencies, the risk of erroneous diagnosis is great unless the appropriate number of cells is studied. We present here Tables based on the binomial distribution relating the frequency of expression of the fragile X in a patient with the sample size required to obtain a probability P of correct diagnosis according to different criteria.

Chromosome Fragility↗
PubMed1983

[Application of terms of probability theory in embryology and teratology].

The aim of the paper was to show that accurate morphological statements can be made with the help of simple concepts of the theory of probability. Binomial distribution was used to find out whether the number of male and female births in large families was random or whether a particular disposition to boys/girls was to be assumed. It was found that the relation was random as a rule. A second question was that of the connection between a number of simultaneous variations and deformities. After the injection of trypan blue, combined deformities were studies in rats and found to be independent of each other, i.e. all had been directly caused by trypan blue.

Abnormalities, Severe Teratoid↗
PubMed1982

Statistical methods in ophthalmology: an adjustment for the intraclass correlation between eyes.

For the cases of normally- and binomially-distributed outcome variables, methods are presented for analyzing ophthalmologic data to which a person may have contributed two eyes worth of information, the values from the two eyes being highly correlated. A frequently-used method of analysis, where each eye is treated as an independent random variable, is shown to be invalid in the presence of intraclass correlation: it yields true p-values two to six times as large as nominal p-values when realistic assumptions are made about the degree of correlation between eyes. These results may be applicable to other medical specialties, such as otolaryngology, where highly-correlated replicate observations are obtained from individuals.

Analysis of Variance↗
PubMed1982

Approximate confidence intervals for probabilities of survival and quantiles in life-table analysis.

For survival probabilities with censored data, Rothman (1978, Journal of Chronic Diseases 31, 557-560) has recommended the use of quadratic confidence limits based on the assumption that the product of the 'effective' sample size at time t and the life-table estimate of the survival probability past time t follows a binomial distribution. This paper shows that the proposed confidence limits are asymptotically correct for continuous survival data. These intervals, as well as those based on the arcsine transformation, the logit transformation and the log(--log) transformation, are compared by simulation to those based on Greenwood's formula--the usual method of interval estimation in life-table analysis. With large amounts of data, the alternatives to the Greenwood method all produce acceptable intervals. On the basis of overall performance, the intervals suggested by Rothman are preferred for smaller samples. Any of these methods may be used to generate confidence sets for the median survival time or for any other quantile.

Actuarial Analysis↗