A method for the in situ measurement of the electrical quantities in frog skin

A method allowing the measurement of the electrical quantities related to the physiological functions of the frog skin in situ is presented. The method allows the performance of several experiments on the same pithed animal, which remains alive for a number of days. The preparation is very stable, and the electric potential difference and short-circuit current values are higher than in isolated skin. The theory of measurement and the possible systematic errors are discussed. The possibilities of the method are evaluated on comparing the pH and temperature dependence of the electrical quantities in situ with previous measurements on isolated skin.     

相机陷阱法在潮间带底栖蟹类群落生态学中的应用研究

潮间带大型底栖动物调查是滨海湿地生物多样性监测的重要环节。目前普遍应用的传统侵入性调查方法（挖掘法、手捕法和陷阱诱捕法）存在干扰强、耗时久和劳动密集等问题,无法客观反映活动性较强的蟹类等重要功能类群的群落结构和物种多样性。对陆地野生动物研究中常用的相机陷阱法进行了符合潮间带应用条件的便携式设计,并以红树林蟹类为例,通过与3种传统侵入性调查方法进行对比,探讨相机陷阱法在潮间带底栖蟹类群落生态学研究中的应用。结果表明：（1）相机陷阱法在种群密度测定方面比挖掘法提高2.1倍,比手捕法提高10.3倍,比陷阱诱捕法提高16.3倍;（2）相机陷阱法在调查物种数方面均高于3种传统侵入性调查方法,适用于沙蟹科（Ocypodidae）和方蟹科（Grapsidae）蟹类调查;（3）相机陷阱法对个体大小选择性弱,采样更加全面;（4）相机陷阱法在群落alpha多样性（Shannon-Wiener指数）、beta多样性（样方-多度矩阵总方差Var （Y））和功能多样性（Rao二次熵和功能离散度）调查方面整体不弱于侵入性调查方法。此外,相较于侵入性调查方法,相机陷阱法对沉积物结构破坏小、不干扰蟹类群落结构,在兼顾数据丰富性的同时又具有高效性。然而,由于相机陷阱法基于蟹类底表活动性,无法适用于冬季调查、夜行性蟹类和游泳型蟹类调查。未来,相机陷阱法的发展将与基于深度学习的图像处理技术结合以满足数据处理需求。研究揭示了相机陷阱法在潮间带底栖蟹类群落中的应用优越性与局限性,为潮间带大型底栖动物群落生态学的研究提供技术支撑。     

Investigations concerning the application of the cross-correlation method in cardiac output measurements

ABSTRACT: BACKGROUND: In spite of numerous non-invasive examinations the "gold clinical standard" of cardiac output measurements is the invasive pulmonary artery catheterization by means of the Swan-Ganz catheter and the application of the thermodilution method to estimate the blood flow. The results obtained by means of thermodilution are sensitive to many physical and biological disturbances. The unreliability of this method amounts to 20-45% and depends on the given variant of the method. Therefore some other method, more accurate and resistant to disturbances, was looked for. This paper presents a new approach to cardiac output measurements, based on cross-correlation signal analysis. The goal of investigations was to verify experimentally the application of the cross-correlation method of cardiac output measurements. RESULTS: In 99.2% of the examined cases the extreme of the cross-correlation function was easy to be estimated by numerical algorithms. In 0,8% of the remaining cases (with a plateau region adjacent to the maximum point) numerical detection of the extreme was inaccurate. The typical unreliability of the investigated method amounted o 5.1% (9.8% in the worst case). Investigations performed on a physical model revealed that the unreliability of cardiac output measurements by means of the cross-correlation method is 3-5 times better than in the case of thermodilution. CONCLUSIONS: The performed investigations and theoretical analysis have shown, that the cross-correlation method may be applied in cardiac output measurements. This kind of measurements seems to be more accurate and disturbance-resistant than clinically applied thermodilution.     

On the Use of the Negative Binomial in Epidemiology

The use of the negative binomial, or the method of inverse sampling (e.g. (1), (2)), is suggested for prospective studies. This method usually has the advantage of fostering an early decision on the statistical significance of some etiological factor in examining successive patient records. Several limiting situations for the distribution are discussed regarding the prevalence of a disease. An example illustrates the method.     

Discrepancies in the Enumeration of Escherichia coli

Stationary-phase cells of Escherichia coli were enumerated by the pour plate method on Trypticase soy agar containing 0.3% yeast extract (TSYA), violet red-bile agar, and desoxycholate-lactose agar, and by the most-probable-number method in Brilliant Green-bile broth and lauryl sulfate broth. Maximum counts were assumed to be those on TSYA. In general, numbers detected were lower with the selective solid media and higher with the selective liquid media. Inhibitory effects, especially on selective solid media varied with the strains of E. coli. The lower detection on selective solid media was partly due to the stress induced in some cells by the temperature of the melted media used in the pour plate method. These cells apparently failed to repair and form colonies in the selective media. Improved detection on the selective solid media was achieved by using 1% nonfat milk solids, 1% peptone, or 1% MgSO(4).7H(2)O in the dilution blanks. Higher detection on selective agar media was effected by surface plating or by surface-overlay plating of the cells. The surface-overlay method appeared to be superior for the direct enumeration of E. coli in foods.     

Evaluation of the effectiveness of the use of specific hemosorption in acute experimental pancreatitis

An effective method of plasma proteinases (trypsin, chymotrypsin. elastases) removal in dogs with acute pancreatitis has been suggested. The method is based on plasmasorption, using human urine acid-stable proteinase inhibitor immobilized on sepharose. The procedure of plasmasorption reduces proteinase levels in dogs with acute pancreatitis to 35-70%, with the animal life-span prolonged 8-fold.     

Studies on the potency test of HB vaccine by the parallel line assay method in guinea pigs

The parallel line assay method was applied on the potency test of HB vaccine in guinea pigs. The applicability of the method was investigated to obtain information on the possible effect of inactivation process of HBs antigen, on the magnitude of adjuvant effect of aluminum compound and so on. The precision of the method was found to be comparable to those of diphtheria and tetanus toxoids.     

Analysis of errors in determining the aspiration dosage in aerosol immunization and in the experimental study of aerogenic infections

The present work deals with the factors affecting the accuracy of the dosage of vaccinal preparations in the aerosol immunization of animals in a dynamic chamber. The method for analysis of errors in the determination of the aspiration dose is proposed. The method is based on mathematical models describing the main parameters of aerosols and the respiratory factors of the animals, the errors of the techniques and equipment used for immunization. The errors in the determination of the dose have been shown to decrease the reliability of results obtained in the evaluation of respiratory ED50 of vaccinal preparations and to impose limits on the required number of experimental animals.     

Method for the quantitative study of the growth of fibroblastic cells in tissue culture

The method is elaborated for a quantitative evaluation of hypodermic fibroblast element growth in tissue culture of albino rats. The method is based on determination of the growth activity and intensity for each of the explant growth zones (compact, necwork-like zones and zone of migrating elements). The method permits a rapid and an exact evaluation of the influence of different substances added to the culture medium.     

Registration of changes in the nucleoide conformation based on the analysis of the time dependence of viscosity

The sensitivity of the method of anomalous time dependence of viscosity to changes in the conformation of DNA-protein complexes (such as nucleoide) by the action of (1) nalidixic acid on cells and (2) one- and two-charged ions Na+, Cl-, Cu2+, Ca2+, Mg2+, Zn2+, SO4(2-) on Escherichia coli cells has been studied. The data obtained suggest that the method anomalous time dependence of viscosity is highly sensitive to the conformation of high-molecular DNA-protein complexes. It was shown that the method anomalous time dependence of viscosity can be used to register cell sensitivity to changes in the concentration of one- and two-charged ions in suspension.     

Calculation of the Root/Shoot Ratio in the Models of Higher Plant Organogenesis

A new method for calculating the assimilate distribution between plant shoots and roots in dynamic models of production process for agricultural crops is suggested. The method is based on direct calculation of the dynamics of photosynthate accumulation and absorption rates of nitrogen compounds in the plant root system. The hypothesis underlying this method is that all mobile compounds entering the plant are completely utilized for the production of structured biomass. Unlike the method of distribution keys, which is widely used in similar models, the suggested procedure accounts for adaptive plant responses to both uncontrolled weather conditions and mineral nutrition. The suggested method was implemented as software within the framework of Agrotool (version 3) simulation system. Verification of the method in many years' field experiments with barley confirmed its efficiency and showed a satisfactory accuracy of model calculations.     

The role of sex in the determining the variability of the autoantibody levels in humans

Dependence of human antibody levels determined by immunoenzyme method on sex of an individual was studied. No significant impact of sex differences on phenotypic dispersion of the levels analysed both in healthy individuals and in those suffering from rheumatic diseases was shown. The data obtained point to the necessity of accounting sex in interpretation of the results of clinical observations.     

Use of protein A in the immunosorbent analysis of antibodies to the tick-borne encephalitis virus

The results of the studies made with a view to developing the method for the determination of specific antibodies to the antigen of tick-borne encephalitis virus in human blood serum and liquor are presented. The method is based on the capacity of Staphylococcus aureus protein A to bind with Fc-region of immunoglobulins, which makes it possible to use this protein as the "second" system of antibodies. The conditions for the sorption of the antigen on polystyrene test tubes and for binding 125I-or horse radish peroxidase-labeled protein A preparations with antibodies have been determined, and the method has been approved in tests made on sera and liquor obtained from donors and tick-borne encephalitis patients.     

A specific method of high sensitivity for the determination of adenosine in the incubation medium of fat tissue

A suitable method for the measurement of adenosine in the incubation medium of fat tissue (200-500 mg) has been developed. The method is based on the specificity of the adenosine deaminase reaction and on the high sensitivity of a fluorescent method for adenine derivatives. The decrease of fluorescence in a sample after treatment with this enzyme is used for measuring adenosine in the range of 50-500 pmoles/tube. This method is highly specific and is not affected by other adenine derivatives present in the sample. Instead of acetic acid, perchloric acid was used in the fluorescent reaction, thus increasing the amount of adenosine dependent fluorescence. With this modification of the original fluorescent method, perchloric acid extracts can be used without further processing after deproteinization of the samples. Using this method, we could measure the adenosine release of fat pads of Wistar rats incubated in Krebs-Ringer-albumin buffer without concentration or purification procedures.     

Use of the bioluminescent method for the determination of bacterial adenosinetriphosphate (ATP-metry) in microbiology

The attention of a wide circle of specialists has recently been attracted by different methods for rapid determination of pathogenic microorganisms in biological specimens, environmental objects and foodstuffs, as well as in cases of possible acts of bioterrorism. In this respect the bioluminescent method for determination of adenosine triphosphate (ATP) contained in microbial cells is of interest. The method is based on the interaction ATP, luciferase and luciferin, accompanied by giving off energy in the form of light emission. When compared with routine methods, the use of this method considerably reduces the duration of the analysis, and its high sensitivity is comparable with that of the polymerase chain reaction. In this review the data on the prospects of the practical use of the bioluminescent method of ATP-metry are presented.     

Computed tomography in the diagnosis of endophytic cancer of the stomach

The authors discuss the potentialities of CT in the diagnosis of endophytic stomach cancer. They proposed a method for CT of the stomach based on a pneumatic study of its lumen via a nasogastric probe with graded inflation and repeated CT imaging. The major CT-semiotics of endophytic stomach cancer were obtained. This method should be employed in combination with the existing routine methods of stomach cancer diagnosis, and its efficacy is in direct relation to the quality of preliminary routine x-ray and endoscopic investigations.     

Assessing protein co-evolution in the context of the tree of life assists in the prediction of the interactome

The identification of the whole set of protein interactions taking place in an organism is one of the main tasks in genomics, proteomics and systems biology. One of the computational techniques used by many investigators for studying and predicting protein interactions is the comparison of evolutionary histories (phylogenetic trees), under the hypothesis that interacting proteins would be subject to a similar evolutionary pressure resulting in a similar topology of the corresponding trees. Here, we present a new approach to predict protein interactions from phylogenetic trees, which incorporates information on the overall evolutionary histories of the species (i.e. the canonical "tree of life") in order to correct by the expected background similarity due to the underlying speciation events. We test the new approach in the largest set of annotated interacting proteins for Escherichia coli. This assessment of co-evolution in the context of the tree of life leads to a highly significant improvement (P(N) by sign test approximately 10E-6) in predicting interaction partners with respect to the previous technique, which does not incorporate information on the overall speciation tree. For half of the proteins we found a real interactor among the 6.4% top scores, compared with the 16.5% by the previous method. We applied the new method to the whole E.coli proteome and propose functions for some hypothetical proteins based on their predicted interactors. The new approach allows us also to detect non-canonical evolutionary events, in particular horizontal gene transfers. We also show that taking into account these non-canonical evolutionary events when assessing the similarity between evolutionary trees improves the performance of the method predicting interactions.     

Prognosis of the dynamics and intensity of the epidemic process in viral hepatitis A

The article deals with approaches to the calculation of the annual morbidity rate in virus hepatitis A at the period preceding the season of maximum morbidity, necessary for planning the relevant prophylactic and antiepidemic measures in due time. The method for calculating the monthly levels of sporadic morbidity in virus hepatitis A is proposed. This method permits the detection of complications on the epidemic situation, which is necessary for the timely organization of antiepidemic measures. The proposed method for predicting annual and monthly morbidity levels can be used in the practical work of specialists at sanitary and epidemic stations.     

The method of the integral evaluation of the behavioral depression in rats

A new method of the evaluation of behavioral depression was developed based on a ranged scale of changes in a number of depressive symptoms in behavior and general state of animals. The method makes it possible to evaluate the individual expression of depressive symptoms in rats and can be used for revealing a correlation between the decrease in motivation level in depressive animals and alterations of some pathophysiological parameters.     

Application of the Ovarian Teratoma Mapping Method in the Mouse

Murine ovarian teratomas were used to determine recombination percentages for gene-gene and centromere-gene intervals. Data were obtained utilizing a recombinant inbred strain, LTXBJ, and a number of newly developed LT/SvEi congenic strains.--Centromere-gene recombination was measured at 11.3 +/- 1.2% for the centromere of chromosome 7 - Gpi-1 interval and 15.8 +/- 2.4% for the centromere of chromosome 14 - Np-1 interval using the ovarian teratoma method. The centromere - Np-1 interval was measured at 26.5 +/- 3.6% using a standard backcross involving the Rb6Bnr Robertsonian translocation as a centromere marker.--To assess the accuracy of the ovarian teratoma mapping method, we compared the recombination frequency obtained for the Mpi-1-Mod-1 interval on chromosome 9 using the ovarian teratoma method to that obtained using a standard backcross. The recombination percentage was 22.9 +/- 5.4 using the ovarian teratoma method and 18.6 +/- 3.3 using the backcross method, indicating that the two methods produce equivalent estimates of recombination. In addition, for centromere-gene intervals known to be more than 30 cM in length, the ovarian teratoma method was consistent with classical recombination methods, yielding high recombination percentages. We conclude from these results that the ovarian teratoma mapping method is a reliable method for estimating recombination frequencies and the most accurate method available for estimating centromere-gene recombination frequency in the mouse.