[Geographical distribution and statistics of obstetric analgesia in Italy].
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Anesthesia, Obstetrical↗
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The significance of morphometric procedures in the investigation of age changes in cytoarchitectonic structures of human brain.
The investigations were performed on NISSL-stained cytoarchitectonic images of totally 78 human brains (aged between 18 and 111 years) in the frontal area 11 (inside sulcus olfactorius) with 60 samples and in the visual cortex (area 17) with 45 samples. The morphometric measurements were taken by using a semiautomatic equipment. The largest projection areas of neurons were digitized over a drawing mirror. The arrangement of fields made it possible to get values for the total cortex and its layering. During the calculation the age-dependent embedding shrinkage was paid attention to. Therefore, the values concern the fresh tissue. The neuronal and glial densities, the neuronal sizes and size-distributions were calculated by using stereological and statistical principles. The results outline the following points: A basic description of the cytoarchitectonics is given in their qualitative and quantitative aspects. The individual variation shows high differences, which however, are in accordance with a normal statistical distribution. In area 11 we could find a significant difference of neuronal densities between males and females. The cell-sizes and the aging behavior are not different. In area 17 the amount of female brains was too small for statistics. The aging of both areas showed that the densities of neurons and glial cells do not decrease. A small increase may be possible. The neuronal sizes of area 11 are constant up to 60 years, then a distinct decrease can be observed. During aging the size decrease of neurons is very small in area 17. The layer III usually shows a distinct decrease of neuronal size during aging while layer V has a nearly constant size. The results were discussed and compared with other publications. The differences between our results and earlier publications seem to be mainly due to methodical problems. The older papers do and could probably not observe the stereological procedures of measuring and the age differences of the embedding procedures. The main result is that every gray structure of the brain has its own history.
Adolescent↗
Distribution of membrane thickness determined by lineal analysis.
The expected statistical distributions of intercept length are derived in terms of geometrical probability density functions pertaining to plates with known thickness penetrated by lines with random orientation. These expressions provide arithmetic and graphical solutions for obtaining distributions of membrane thickness and reciprocal membrane thickness from empirical distributions of intercept lengths. Furthermore, general relationships between probability density functions of distributions of intercept length and membrane thickness are derived as well as those between their moments. Examples of the application of the method to biological samples are given, and estimated distributions of glomerular basement membrane thickness are compared to those obtained by an independent, direct method. Various sources of bias, which in practice may occur due to departures from the sample model, are discussed and the influence of some of them is estimated. The knowledge of the probability density function of reciprocal intercepts makes it possible to perform a correction of the distribution of measured intercept length, which to some extent eliminates bias.
Animals↗
Stationarity and normality of distribution of rat cortical brain waves.
Establishing the stationarity and statistical distribution of potentials recorded from the nervous system is crucial for the application of frequency analysis. Both parameters were determined in the electrocorticograms of six adult Wistar rats during wakefulness and desynchronized sleep, during both of which desynchronization prevails. Stationarity of the signals was found to occur during at least 20 s in both states of the wakefulness-sleep cycle. A normal distribution was also found for at least 6.7 s. These findings provide strong support for the use of frequency analysis of brain waves as a reliable method to quantify neural electro-oscillograms.
Animals↗
Comparative sensitivity of survival-adjusted chi-square and normal statistics for the mutagenesis fluctuation assay.
Three statistics for analysis of microtitre plate mutagenesis fluctuation tests were studied by simulation, and in enzyme-activated assays of dimethylnitrosamine and diethylnitramine. A survival-adjusted chi 2 statistic ('Gsq') was compared with Katz's normally distributed statistic ('Phi'), and with the survival-independent statistic ('Zsq') of Gilbert. When toxicity was either very low or high, the Phi statistic either could not be evaluated over the whole range of possible background mutant frequencies, or sometimes it indicated unusually high levels of statistical significance, even when the other tests were negative. The survival-adjusted Gsq closely followed the Zsq statistic throughout the experimentally useful range of toxicities and mutant background values, with some improvement in sensitivity. Within the range 80 +/- 10% survival approximately, Katz's statistic 'Phi' was the most sensitive. The choice of statistical test could affect the estimate of the minimal effective mutagenic concentration by a factor of 10-100. For screening unknowns, both types of test (Phi and Gsq (or Zsq] may help in detecting suspect pro-mutagens and in designing a confirmatory assay. Bacterial population statistics are needed to assess the value of statistically positive results.
Cell Survival↗
Voltage-clamp analysis of posttetanic potentiation of the mossy fiber to CA3 synapse in hippocampus.
1. Short-term changes in synaptic efficacy were studied at the mossy fiber (MF) to CA3 (MF-CA3) synapse in the in vitro hippocampus. Monosynaptic excitatory postsynaptic currents (EPSCs) were recorded before and during posttetanic potentiation (PTP) with the use of intracellular recording and single-electrode voltage-clamp (SEVC) techniques. 2. Repetitive stimulation (100 Hz for 1 s) of the MF synaptic inputs to CA3 pyramidal cells resulted in PTP averaging 170 +/- 19% (SE, n = 42) over control and decaying with a time constant (tau p) of 59.7 +/- 5 s(n = 23). Reproducible episodes of PTP could be recorded if low stimulus intensities were used. Also, after MF tetanization, a faster component, termed augmentation, preceded PTP but could not be accurately resolved within the experimental protocol; only estimates of this component are included. 3. Biophysical parameters of the EPSC that were monitored before and during PTP included synaptic conductance (G), synaptic reversal potential (Erev), decay time constant (tau EPSC), and input resistance of the postsynaptic cell. During PTP the EPSC synaptic conductance increased from 9.8 to 32.7 nS (P less than 0.02, n = 6), whereas there was no statistical change in Erev (-6.0 compared with -6.7 mV, n = 6), tau EPSC (4.3 compared with 4.5 ms, n = 9), or postsynaptic input resistance (59 compared with 63 M omega, n = 12). 4. A presynaptic contribution to PTP was studied directly by observing changes in transmitter release during PTP. Presynaptic mechanisms were assessed by determining the ratio of evoked synaptic excitatory postsynaptic potentials (EPSPs) over the total number of stimuli (EPSP-to-stimuli ratio). The ratio of EPSP to stimuli changed from 0.64 to 0.90 (P less than 0.01, n = 7) during PTP. A reduction in the number of synaptic failures can only be explained by a presynaptic mechanism. No assumptions concerning the statistical distribution of transmitter release were necessary because no statistical parameters were determined. 5. Changes in postsynaptic cell properties do not appear to contribute to PTP studied under the present experimental conditions. Direct stimulation of the postsynaptic neuron via the intracellular recording electrode (20-100 Hz/1 s) failed to produce potentiation of the EPSC; in fact, a slight depression was observed at 50 and 100 Hz direct stimulation. Likewise, the postsynaptic input resistance and synaptic Erev did not change during PTP. 6. The specific N-methyl-D-aspartate (NMDA) receptor antagonist D-2-amino-5-phosphonovaleric acid (APV, 20 microM) had no effect on either the magnitude or duration of PTP.(ABSTRACT TRUNCATED AT 400 WORDS)
Action Potentials↗
DNA in situ sensitivity to denaturation as a marker of human breast tumors.
DNA content and in situ sensitivity to denaturation were analyzed by flow cytometry of individual cell nuclei isolated from 40 breast carcinomas, nine fibroadenomas, and 14 samples of normal breast tissue. The extent of DNA denaturation induced by acid was expressed as alpha t, which represents the fraction of DNA staining metachromatically red with the fluorochrome acridine orange. In all cases of normal breast tissue DNA was very sensitive to denaturation and the frequency distribution of alpha t values was unimodal with over 90% of cells having alpha t above 0.6. All fibroadenomas were diploid; four had unimodal alpha t as in normal tissue and five had a bimodal distribution with an additional peak below 0.6. Twenty-seven adenocarcinomas (67%) had a DNA index above 1.0; of these 24 had bimodal alpha t distributions. Among 13 diploid carcinomas 10 had bimodal alpha t distributions. Statistically significant differences were observed in alpha t distributions of normal versus tumor breast tissue (P less than 0.005). In normal tissue and in all tumors a predominant proportion of cells with S and G2 + M DNA content were characterized by DNA resistant to denaturation (alpha t below 0.6). Of interest, the diploid cells from aneuploid tumors which may represent reactive host cells often displayed bimodal distributions of alpha t. These results may be interpreted in light of earlier studies demonstrating increased resistance of DNA to denaturation in diffuse chromatin of proliferating and/or transcriptionally active cells, and greater sensitivity to denaturation of DNA in condensed chromatin of quiescent cells. Thus, the presence of the second peaks representing cells with low alpha t values in breast tumors may indicate a high proportion of proliferating cells, whereas high alpha t populations may represent quiescent and differentiating (condensed chromatin) or dying (pycnotic nuclei) cells. It is likely that the low alpha t diploid cells detected in aneuploid tumors may represent the reactive (transcriptionally active and/or proliferating) infiltrating host cells (i.e., lymphocytes, monocytes) whose presence may also be of prognostic value. The data suggest that a DNA denaturability assay may be useful to characterize tumor and infiltrating host cell populations.
Acridine Orange↗
Extracorporeal irradiation of blood: dosimetry corrected for shortened erythrocyte lifespans.
The amount of radiation delivered to erythrocytes during extracorporeal irradiation of blood (ECIB) has been described using Poisson distribution statistics. The Poisson expression for erythrocyte radiation dose distribution was simplified by considering the slight dilution of blood with fluid that is initially in the extracorporeal tubing. An algorithm was devised that allows curtailed lifespans of irradiated erythrocytes to be taken into account in a short computer program of radiation dosimetry for ECIB. Radiation doses to erythrocytes with and without lifespan corrections are compared.
Blood Cells↗
Lognormal distribution in physical work capacity in young healthy males.
This paper evaluates the statistical distribution of physical work capacity (Vo2 max) in young healthy males. For this purpose, the normally of Vo2 max data, collected on two random samples consisting of 123 and 120 young healthy male volunteers was tested. It is concluded that physical work capacity follows lognormal distribution and the quality of fit has been found to be good as tested by chi2 test.
Disability Evaluation↗
[Rheology and spinning of alkaline solutions of sunflower seed globulin and casein].
The specific demand of sodium hydroxide is determined for the dissolution of sunflower seed globulin, casein and a mixture of them to equal parts. In low protein-containing solutions it depends for sunflower seed globulin very much on the sodium chloride concentration. From sunflower seed globulin, casein and a mixture of them to equal parts are prepared with sodium hydroxide high protein-containing alkaline solutions. Sunflower seed globulin forms temporally a gel phase. After this phase the solution of sunflower seed globulin shows like casein and a mixture of sunflower seed globulin/casein (I:I) pseudoplastic flow. The flow curves of the pseudoplastic solutions are described mathematically with the OSWALDian power statement. By alkaline solutions of casein and sunflower seed globulin/casein (I:I) the flow exponent n is distributed statistically about 0.9, by solutions of sunflower seed globulin a distribution exists about the mean values n = 0.85 and n = 0.50. lg k depends in all protein solutions on the concentration of protein, sodium chloride, sodium hydroxide and on the temperature and time. For all protein solutions exists a linear relation between the logarithm of viscosity and the reciprocal temperature for lg k and I/T, which is derived normally for NEWTONian flow behaviour. In a suitable scope of spinning for all protein solutions are carried out complete factorial experiment, which guide to regression equations of lg k; in the case of sunflower seed globulin are calculated also a regression equation of the flow exponent n. Going out from the parameters of the spinning process the properties of the spun sunflower seed globulin/casein (I:I) fibers are described.
Caseins↗
[Evaluation of the clinical effectiveness of paradentosis therapy (author's transl)].
The x2 test of goodness of fit was used to assess the correlation between empirically determined distributions of a number of characteristics used in parodontology and the model of normal distribution. There was found a more or less pronounced asymmetry in the statistical distributions of some clinical and biochemical tests. It is recommended to use 10g X or square root of x in order to achieve approximation to the normal distribution. Inaccuracies in interpretation of clinical data due to neglect of variations from normal distribution are pointed out.
Diagnostic Errors↗
Nephrotoxicity screening in rats; general approach and establishment of test criteria.
The concept of a nephrotoxicity screening test that is based on quantitative assessment of urine collected under standardized conditions for 15.5 h is presented. One to eight urine collections were performed in large numbers of untreated female Sprague-Dawley rats. Normal values for water consumption, urine volume, pH, and excretion of protein, gamma-glutamyltranspeptidase, malate dehydrogenase, electrolytes, glucose, amino acids, leukocytes, erythrocytes, epithelia, unspecified cells and cylinders were determined. Test criteria were established based on the statistical distribution of these measurements. In rats repeatedly placed in metabolism cages, a statistically significant decrease in leukocyte excretion and an increase in excretion of epithelia and unspecified cells were observed. All other variables did not change with time.
Animals↗
Preventive distinction of patients with primary or secondary hypertension by discriminant analysis of chronobiologic parameters estimated on 24-hour blood pressure patterns.
This investigation deals with a statistical probatory that patients with primary (PH) or secondary (SH) hypertension may be correctly diagnosed by a discriminant analysis of the chronobiologic characteristics computed on the 24-hour blood pressure (BP) patterns. The methodology concerning non-invasive 24-h BP monitoring, chronobiologic analysis and the discrimination process is detailed. Substantial dissimilarities were found in the statistical distribution for systolic and diastolic BP rhythmometric parameters (mesor, amplitude and acrophase) by a retrospective assessment of two groups, consisting of 54 patients with PH and 16 patients with SH. The group-related distribution for rhythmometric parameters was found to be significantly different to generate a statistically significant intergroup discriminatory boundary. The discriminant analysis correctly diagnosed patients with PH and SH in a percentage of about 91% and 63%, respectively. The high incidence of success is convincing that the combination of 24-h BP monitoring/chronobiologic analysis/discrimination process cna be a practical tool for confidently selecting patients with a presumable PH or SH.
Adolescent↗
Dangers and problems in calculating coefficients of a sum of exponential functions.
The use of the computer in making calculations has led increasingly to the estimation of parameters of exponential functions from point experimental measurements. This involves the use of techniques such as logarithmic transformations and criteria (especially that of the least squares), of which the use is not always justified. Radioactivity measurements raise special problems as they are subject to a statistical distribution of the Poisson type. The authors propose a method based on the statistical criterion of "maximum likelihood" which permits tests of the number of exponentials from point measurements (in practice, this method is valid for one or two exponentials), and also the calculation of parameters more satisfactorily than customary methods.
Mathematics↗
[Distribution of 5-methylcytosine in phage lambda genome methylated by DNA methylase Eco RII].
The distribution of 5-methylcytosine in Eco RI-Bam HI fragments of phage lambda DNA in vitro methylated by Eco RII methylase has been studied. The general picture of distribution of methylated sites in phage lambda DNA is slightly different from the statistical distribution. However, the sites have been found, where the distribution of 5-methylcytosine is not accidental. A complete absence of 5-methylcytosine in the J-fragment, a genome lambda area essential for site-specific recombination, has been found. The absence of Eco RII is supposed to be the best protection of this area of phage genome from the increased mutagenesis, characteristic for nucleotide sequences methylated by DNA-methylated Eco RII and Eco RII type.
5-Methylcytosine↗
Specificity of auditory brainstem response audiometry criteria in acoustic neuroma screening as a function of deviations of reference values in patients with cochlear hearing loss.
On the basis of 79 patients with cochlear hearing loss, the statistical distribution of two criteria commonly used in auditory brainstem response audiometry (ABR) was analyzed: the interaural V latency difference (ILD V) and the interaural difference of I-V interpeak interval (ID I-V). The distribution of both criteria was Gaussian. By evaluating their standard deviations the percentages of statistical false-positives were estimated. The estimated results were 24% false-positive findings using the decision criterion ILD V greater than 0.2 ms and 5.4% false-positive findings using ID I-V greater than 0.3 ms. This corresponds closely to the actual false-positive ABR rates obtained in this sample: 21.5% and 6.3%, respectively. In a separate series of 301 unselected cases with asymmetric sensorineural hearing loss, 29 ABRs were suspect for retrocochlear pathology. In 20 patients, ABRs were absent due to severe hearing loss. Retrocochlear pathology could be confirmed in only 2 cases (both from the group with ABR present). Thus, 47 ABRs (15.7% of 299) were false-positive.
Cochlear Diseases↗
On the statistical validity of standards used in profile monitoring of health care.
In current methods of profile monitoring, standards of acceptability (cut-offs) are set either by consulting panels of experts, or by selecting an arbitrary point (e.g., the 75th percentile) on the profile (statistical distribution). However, experts have only vague ideas of what outcome rates ought to be, while profile statistics stem from samples for which unknown percentages of cases have received acceptable care. Poorly chosen standards could cause profile monitoring to be ineffective, inefficient, or unnecessarily disruptive. A new method proposes to set standards by using statistics for which the percentage of adequate care has been predetermined by examining the process of care. Plans to circumvent the pitfalls involved are described, as are two approaches to estimating the degree of process adequacy from routinely produced outcome rates.
Hospitals↗
Endocytosis via galactose receptors in vivo. Ligand size directs uptake by hepatocytes and/or liver macrophages.
We followed the intrahepatic binding and uptake of variously sized ligands with terminal galactosyl residues in rat livers. The ligands were administered to prefixed livers in binding studies and in vivo and in situ (serum-free perfused livers) in uptake studies. Gold sols with different particle diameters were prepared: 5 nm (Au5), 17 nm (Au17), 50 nm (Au50) and coated with galactose exposing glycoproteins (asialofetuin (ASF) or lactosylated BSA (LacBSA)). Electron microscopy of mildly prefixed livers perfused with LacBSA-Au5 in serum-free medium showed ligand binding to liver macrophages, hepatocytes and endothelial cells. Ligands bound to prefixed cell surfaces reflect the initial distribution of receptor activity: pre-aggregated clusters of ligands are found on liver macrophages, single particles statistically distributed on hepatocytes and pre-aggregated clusters of particles restricted to coated pits on endothelial cells. Ligand binding is prevented in the presence of 80 mM N-acetylgalactosamine (GalNAc), while N-acetylglucosamine (GlcNAc) is without effect. Electron microscopy of livers after ligand injection into the tail vein shows that in vivo uptake of electron-dense galactose particles by liver cells is size-dependent. Using a LacBSA-Au preparation with heterogeneous particle diameter (2.2-11.7 nm) we found that hepatocytes take up only ligands up to the size of 7.8 nm, whereas particles of all sizes available in this experiment are found in liver macrophages and endothelial cells. ASF-Au17 and LacBSA-Au17 are endocytosed by liver macrophages and endothelial cells, but not by hepatocytes. ASF-Au50 is taken up by liver macrophages only. In vivo uptake by liver macrophages is mediated by galactose-specific recognition as shown by inhibition with GalNAc. Some 52-65% inhibition was measured in in vivo experiments and 78% inhibition in in situ experiments. GlNAc showed no inhibitory effect. Furthermore, we measured uptake of [125J]ASF and of [125J]ASF adsorbed to Au17 by the different cell populations of rat livers in vivo. While the bulk of the molecular ligand is found in the hepatocyte fraction, the particulate ligand is located in the sinusoidal fraction.
Animals↗