Small Samples Of Biological Material Research Articles

Сytokines as promising diagnostic and prognostic biomarkers of microvascular complications of diabetes

Classical knowledge about the pathogenesis of diabetes and its complications in recent years has been supplemented by ideas about the role of chronic inflammation. It has been established that inflammatory reactions play a role in the beta cell dysfunction, the formation of insulin resistance and remodeling of the vascular wall. Cytokines, soluble low molecular weight proteins and peptides that perform informational and regulatory functions, play central role in the development of inflammation. A wide range of biological activity and involvement in many aspects of pathogenesis make it possible to consider cytokines as promising molecules for diagnosing and predicting the complications. In this review, we summarize data from studies that assessed the role of cytokines as diagnostic and prognostic markers for the development of microvascular diabetic complications. Current data indicate that angiogenic and pro-inflammatory cytokines (VEGF, TNF-α, IL-6, IL-8, IL-15, IL-17, MCP-1, IP-10, INF-γ, PEDF, etc.) are promising biomarkers for proliferative diabetic retinopathy, especially when their local production is assessed (in vitreous, aqueous humor and tears). The role of these molecules as biomarkers of non-proliferative diabetic retinopathy and diabetic macular edema needs further research. Serum proinflammatory and fibrogenic cytokines (primarily MCP-1, IL-6, TNF-α, YKL-40, TGF-β and bFGF) and cytokine receptors (sTNFR1, sTNFR2) are considered as promising diagnostic and prognostic markers of diabetic kidney disease. Urinary excretion of IL-6 and MCP-1 turned out to be a predictor of the progression of diabetic nephropathy. Multi-bead assay and mass spectrometry make it possible to study cytokine panels in small samples of biological material. Combined biomarkers, including several cytokines, may increase the reliability of the prognosis of diabetic complications.

Inhibitory Effect of Metformin on Oxidation of NADH-Dependent Substrates in Rat Liver Homogenate

Metformin is widely used in the treatment of Type 2 diabetes, however, mechanisms of its antihyperglycemic effect were not yet fully elucidated. Complex I of mitochondrial respiration chain is considered as one of the possible targets of metformin action. In this paper, we present data indicating that the inhibitory effect of metformin can be tested also in liver homogenate. Contrary to previous findings on hepatocytes or mitochondria under our experimental conditions, lower metformin concentrations and shorter time of preincubation give significant inhibitory effects. These conditions enable to study the mechanism of the inhibitory effect of metformin in small samples of biological material (50-100 mg wet weight) and compare more experimental groups of animals because isolation of mitochonria is unnecessary.

Spindle disturbances in human‐hamster hybrid (AL) cells induced by mobile communication frequency range signals

The production of spindle disturbances in FC2 cells, a human-hamster hybrid (A(L)) cell line, by non-ionizing radiation was studied using an electromagnetic field with a field strength of 90 V/m at a frequency of 835 MHz. Due to the given experimental conditions slide flask cultures were exposed at room temperature in a microTEM (transversal electromagnetic field) cell, which allows optimal experimental conditions for small samples of biological material. Numerical calculations suggest that specific absorption rates of up to 60 mW/kg are reached for maximum field exposure. All exposure field parameters--either measured or calculable--are precisely defined and, for the first time, traceable to the standards of the SI system of physical units. Compared with co-incident negative controls, the results of two independently performed experiments suggest that exposure periods of time from 0.5 to 2 h with an electric field strength of 90 V/m are spindle acting agents as predominately indicated by the appearance of spindle disturbances at the ana- and telophase stages (especially lagging and non-disjunction of single chromosomes) of cell divisions. The spindle disturbances do not change the fraction of mitotic cells with increasing exposure time up to 2 h. Due to the applied experimental conditions an influence of temperature as a confounder parameter for spindle disturbances can be excluded.

A drop tower for controlled impact testing of biological tissues

Impact damage, in particular to tissues such as articular cartilage, is a recognised source of morbidity. To understand better the clinical outcomes, it is important to know the mechanics of the damage sustained and the biological response of cells to rapidly applied forces and subsequent tissue disruption. An instrumented drop tower has been designed to enable controlled impact loads to be applied to small samples of biological materials. Impact severity can be controlled by using impactors of different masses and various drop heights. Force and deceleration at impact are recorded at 50,000 samples s −1 by a force transducer under the sample and an accelerometer on the impactor. Repeatability was tested on rubber washers and coefficients of variation were found to be better than 8% for dynamic stiffness, 3.4% for stress and 4.3% for strain. Initial tests on isolated biopsies of articular cartilage showed that at an initial strain rate of 916 s −1, the peak dynamic modulus of human femoral head cartilage was 59 MPa, and for a bovine biopsy the initial strain rate and corresponding peak dynamic modulus were 3380 s −1 and 130 MPa, respectively. The equipment described is capable of applying an impact load to small biopsies of tissue with a defined energy and velocity and measuring deformation and load at high rates of loading.

High-resolution respirometry–a modern tool in aging research

Alterations in mitochondrial function are believed to play a major role in aging processes in many species, including fungi and animals, and increased oxidative stress is considered a major consequence of altered mitochondrial function. In support of this theory, a lot of correlative evidence has been collected, suggesting that changes in mitochondrial DNA accumulate with age in certain tissues. Furthermore, genetic experiments from lower eukaryotic model organisms, indicate a strong correlative link between increased resistance to oxidative stress and an extended lifespan; in addition, limited experimental evidence suggests that the inhibition of mitochondrial function by selected pharmacologically active compounds can extend lifespan in certain species. However, changes in mitochondrial function may affect aging in a different way in various tissues, and a clear statement about the role of mitochondrial deterioration during physiological aging is missing for most if not all species. At this point, respirometric analyses of mitochondrial function provide a tool to study age-associated changes in mitochondrial respiratory chain function and mitochondrial ATP production within living cells and isolated mitochondria. In the recent years, new instruments have been developed, which allow for an unprecedented high-resolution respirometry, which enables us to determine many parameters of mitochondrial function in routine assays using small samples of biological material. It is conceivable that this technology will become an important tool for all those, who are interested in experimentally addressing the mitochondrial theory of aging. In this article, we provide a synopsis of traditional respirometry and the advances of modern high-resolution respirometry, and discuss how future applications of this technology to recently established experimental models in aging research may provide exciting new insights into the role of mitochondria in the aging process.

The X Chromosome and the Female Survival Advantage

Despite differences in research traditions, the disciplines of genetics, epidemiology, and demography are becoming increasingly integrated in health-related research. The enormous development within genetic technology, with the possibility of genotyping thousands of variants from small samples of biological material obtained by non-invasive methods, now makes it feasible to include genetic information in epidemiologic and demographic studies. Simultaneously, new insight can be obtained from hybrids of methods and data from the three disciplines. This paper illustrates how a genetic observation combined with demographic insight and a modified genetic-epidemiologic design (a twin study) provides evidence that part of the sex difference in survival can be attributed to the fact that females have two X chromosomes and males have only one, a result that is of potential interest for genetics, epidemiology, and demography.

Method for the measurement of antioxidant activity in human fluids

Aim—To develop a new, simple, and cheap method for estimating antioxidant activity in human fluids. Methods—The assay measured the capacity of the biological fluids to inhibit the production of thiobarbituric...

Whole blood chromium level and chromium excretion in the rat after zinc chromate inhalation.

Studies on absorption and excretion of chromium in the rat exposed to known atmospheric concentrations of zinc chromate in an inhalation chamber and the influence of diurnal variations in physical activity have been carried out. Chromium analyses were performed on samples of blood, urine and faeces using a method for determining chromium in small samples of biological material based on flameless atomic absorption spectrometry. Zinc chromate is absorbed quickly during exposure and excreted mainly via urine. An accumulation of chromium in blood was observed, followed by a slow elimination. It is suggested that chromium from zinc chromate enters the blood in the hexavalent state.

Determination of silver in biological materials by high-frequency plasma-torch emission spectrometry

Nanogram amounts or silver in small samples of biological materials can be determined by high-frequency plasma-torch emission spectrometry. Samples are digested with perchloric and nitric acids, silver is collected with a bismuth iodide carrier, and the precipitate is decomposed with concentrated nitric acid before dilution. Bismuth shows an enhancing effect on the silver emission at 328.06 nm, and the sensitivity is further improved by elimination of moisture in the aerosol with a second condenser at -3 to -5°C. The detection limit is 0.5 ng per 0.2 ml of sample solution. Condensed milk and whole blood were analyzed satisfactorily.

Instrumental neutron activation analysis for mercury in dogs administered methylmercury chloride: use of a low energy photon detector.

Mercury was determined by nondestructive neutron activation analysis in samples of brain tissue from beagles fed methylmercury chloride. The mercury concentration was not uniformly distributed throughout the central nervous system and the fastest rise in concentration occurred in components of the visual system. The analytical procedure was capable of measuring mercury instrumentally and routinely in small samples of biological materials at approximately the 0.2-ppM level within a few days after irradiation with short counting times. Comparative measurements showed that mercury determination based on /sup 197/Hg could be done With greater sensitivity by using a Ge(Li) low-energy photon detector rather than a conventional high-resolution, high-efficiency coaxial Ge(Li) detector. (auth)

Gas chromatography of volatile compounds in small samples of biological materials.

Analysis of the volatile constituents of insect glands by GC without the addition of solvents is described. With this adaption of solid sampling technique, reaction GC can also be applied directly to biological materials.

The simultaneous determination of zinc and cadmium in biological materials by neutron activation analysis

A method for the simultaneous determination of zinc and cadmium is described which is suitable for the analysis of small samples of biological material. Following neutron activation and a simple ion exchange separation zinc and cadmium are identified and assayed by gamma ray spectroscopy. The sensitivity of the method is about 3 × 10 −8 g for cadmium and about 2 × 10 −7 g for zinc. The method has been applied to the determination of cadmium and zinc in subcellular fractions prepared from rat testes and kidney. Analysis of a standard kale powder yielded the values of 32·8 ± 3·2 μg/g for zinc and 0·89 ± 0·16 μg/g for cadmium.

The simultaneous determination of manganese and copper in biological material by neutron activation analysis

A method for the simulataneous determination of manganese and copper in small samples of biological material is described. After neutron activation and wet ashing, a manganese-copper fraction is prepared and the radioactivity due to 56Mn and 64Cu is determined by gamma ray spectroscopy. The limits of detection are 2 × 10 −9 gfor manganese and 2 × 10 −8g for copper. The method was used to analyse a standard kale powder and the following concentrations of manganese and copper were found. Manganese 11·4 ± 0·28 μg/g; Copper 4·12 ± 0·04 μg/g dry powder.

CONTINUOUS TURBIDIMETRIC ANALYSIS OF PH DEPENDENT BIOLOGICAL COALESCENCE PROCESSES.

The method described allows rapid analysis, by pH modulation, of the coalescence of small samples of biological materials in dilute suspensions. Specifically, agglutination of various species of viruses and bacteria at their isoelectric points, and the polymerization process of the muscle protein actin are investigated. A typical time of analysis is 20 sec, and 5 ml of suspensions as dilute as 0.2 mg/ml are sufficient for most viruses investigated.

An improved fume hood for perchloric acid digestions of biological materials

An all-glass hood that can be used for perchloric acid digestion of small samples of biological materials is described. It offers an efficient, rapid inexpensive technique for wet ashing.

Estimation of Mercury in Biological Material by Neutron Activation Analysis.

Neutron activation analysis combined with chemical separation is a quick, accurate method for the estimation of Hg in small samples of biological materials. After nitric-sulfuric acid digeston of the activated sample, a precipitation separation is combined with a gravimetric yield determination. The activity is detected by scintillation counting.

A Vibrator for Treating Small Samples of Biological Materials

A Vibrator for Treating Small Samples of Biological Materials

Determination of Moisture

SEVERAL writers have recently discussed in NATURE1,2,3 methods for the determination of the moisture content of small samples of biological material. It has occurred to us that the method we have described4 for the measurement of moisture in electrical insulating materials might be of great use in this connexion. In brief, the method consists of the removal of moisture from the specimen in vacuo the moisture being retained in the specimen during the initial evacuation by cooling in solid carbon dioxide. The moisture removed on heating the sample to a constant temperature is then measured by observing the water vapour pressure produced at atmospheric temperature in a globe of known volume. Complete removal of the water is not attempted, but a graphical extrapolation is used to determine the total moisture content from the measured equilibrium water vapour pressure.