Densitometric evaluation at quantitative microradiography

Summary The different factors influencing the accuracy of quantitative microradiography have been investigated. The evaluation of densitometric measurements for dry mass determinations has been improved considerably by the introduction of polynomial regression analysis of the output signals for the reference system. Computer analysis has made it possible to extend the number of measurements thereby increasing the precision. The total random error varied between 4 and 5 per cent.     

Treatment of Soft-tissue Injuries by Pulsed Electrical Energy

Twenty pairs of patients matched for sex, age, weight, and degree of trauma were treated either with an active Diapulse machine emitting pulsed, high-frequency electrical energy or with a non-active placebo machine. They were examined for swelling, pain, and disability before treatment and after three days under double-blind conditions. The results show that the pulsed, high-frequency electrical treatment has a definite biological effect on recently injured soft tissues, especially in the reduction of pain and disability.     

Folate-conjugated iron oxide nanoparticles for solid tumor targeting as potential specific magnetic hyperthermia mediators: synthesis, physicochemical characterization, and in vitro experiments

New folate-conjugated superparamagnetic maghemite nanoparticles have been synthesized for the intracellular hyperthermia treatment of solid tumors. These ultradispersed nanosystems have been characterized for their physicochemical properties and tumor cell targeting ability, facilitated by surface modification with folic acid. Preliminary experiments of nanoparticles heating under the influence of an alternating magnetic field at 108 kHz have been also performed. The nanoparticle size, surface charge, and colloidal stability have been assessed in various conditions of ionic strength and pH. The ability of these folate "decorated" maghemite nanoparticles to recognize the folate receptor has been investigated both by surface plasmon resonance and in folate receptor expressing cell lines, using radiolabeled folic acid in competitive binding experiments. The specificity of nanoparticle cellular uptake has been further investigated by transmission electron microscopy after incubation of these nanoparticles in the presence of three cell lines with differing folate receptor expression levels. Qualitative and quantitative determinations of both folate nanoparticles and nontargeted control nanoparticles demonstrated a specific cell internalization of the folate superparamagnetic nanoparticles.     

A simple,rapid, and sensitive DNA assay procedure

A simple and rapid assay for quantitative determinations of DNA in crude homogenates is described. The method is based on the enhancement of fluorescence seen when bisbenzimidazole (Hoechst 33258) binds to DNA. Crude homogenates in which chromatin has been dissociated with high salt buffer can be assayed directly and reliably in a few minutes. The dissociation of chromatin is critical to accurate determinations of DNA in biological materials using this method. The assay can detect as little as 10 ng of DNA with rather unsophisticated instrumentation.     

An automatic gas counter for quantitative micro-determinations of tritium in biological material

An automatic microcounter for quantitative determinations of tritium has been developed. It has a background of 0.5 cpm and a constant and quench-free efficiency of 57.4 ± 2.1% ($\text{E}{}^2\text{b}$ 6600). Radioactivities of 2 pCi can be measured with a standard deviation of ±10% using a 1-hr counting time. It is particularly adapted for tritium microassay from biological material in which tritium is converted to a gaseous state by a single step combustion and reduction method, utilizing a mixture of metallic zinc and anhydrous sodium carbonate. Samples weighing up to 2 mg can be measured using sample ampules made of Pyrex glass with outer diameter of 5 mm and length of 30 mm. The material costs are extremely low and one technician can load and scal over 100 samples in a day. The apparatus may have significance as an additional instrument beside liquid scintillation counters in the region of radioactivities below 20 pCi. The method has been successfully used in investigations concerning steroid metabolism in rat adrenal cortex and testis. Specific activities have been determined from tissue samples weighing 1 μg and less.     

Cuticular sclerotization in the honeybee (Apis mellifera adansonii)

Summary A micromethod has been developed for quantitative determinations of ketocatechols released by acid hydrolysis from samples of sclerotized insect cuticle, weighing from 0.1 to 5 mg. The method has been used to follow the changes in yield of ketocatechols from five different types of cuticle during honeybee development. Samples from workers, drones, and queens have been analyzed. The increase in yield of ketocatechols is most pronounced during the period of pharate development when abdominal cuticle is stiffened and the cuticular proteins become insoluble.     

The chemical determination of section thickness

Summary In quantitative histochemistry it is frequently desirable to know the exact thickness of the sections. The nucleic acid content of the tissue has been used as the basis of a method for determining section thickness. Such determinations agree remarkably well with the setting on the cryostat microtome although considerable variations in thickness can occur in sections cut at different speeds.     

The measurement of iron in rat liver tissue and subcellular fractions using atomic absorption spectroscopy.

To permit the measurement of iron in small amounts of liver tissue or subcellular fractions, a procedure based on wet ashing and atomic absorption spectroscopy has been developed. This procedure, which can detect iron down to a concentration of 0.1 mug/ml, has been used with ferric chloride and Jectofer (iron-citric acid-sorbitol complex) solutions as well as liver homogenates and subcellular fractions. Interference from constituents of liver tissue has not been observed and measurements on fractions appear to be quantitative. Individual determinations had a variability of approximately 10%.     

A QconCAT informatics pipeline for the analysis, visualization and sharing of absolute quantitative proteomics data

Absolute protein concentration determination is becoming increasingly important in a number of fields including diagnostics, biomarker discovery and systems biology modeling. The recently introduced quantification concatamer methodology provides a novel approach to performing such determinations, and it has been applied to both microbial and mammalian systems. While a number of software tools exist for performing analyses of quantitative data generated by related methodologies such as SILAC, there is currently no analysis package dedicated to the quantification concatamer approach. Furthermore, most tools that are currently available in the field of quantitative proteomics do not manage storage and dissemination of such data sets.     

Reactions of thiosulfate and sulfite ions with DTNB: interference in sulfhydryl group analysis

DTNB has been found to react quantitatively with sulfite ion liberating two moles of 3-carboxylato-4-nitro-thiophenolate ion. While this reaction provides a quantitative measurement of sulfite ion, it also provides quantitative interference with the determination of sulfhydryl groups in proteins. Thiosulfate also interferes with the sulfhydryl determinations using DTNB and the equilibrium constant for the reaction formulated as Eq. (3) is (4.8 ± 0.2) × 10^?2 at pH 7.75 and at ionic strength of 0.4.     

A semiautomatic instrument for the radioautographic coating technique.

By means of a mechanical coating instrument a fast, simple method to coat specimens with liquid nuclear track emulsion has been devised for quantitative light and electron microscopic radioautography. In both cases, the section is mounted on a glass slide. After the vertically held slide has been immersed in the melted emulsion, the instrument withdraws it at a slow, constant speed. As a result, the specimen is coated with a thin, uniform emulsion layer composed of homogeneously distributed silver bromide crystals. The thickness of the emulsion coat may be standardized by selection of an optimal combination of emulsion dilution, temperature and withdrawal speed.     

Automated high-performance liquid chromatographic assay of enzymatic activities

High-performance liquid chromatography (HPLC) is a powerful technique which enables a reliable and quantitative determination of enzyme activities. The purpose of the work reported here was to develop an automatic assay of enzymatic activity. Using an automatic sample processor and injector, a program was developed which allows the complete automation of each step of analysis (calibration, enzymatic reaction, HPLC determination). This program can be adapted to different experimental requirements as each step can be performed independently and each input (time, volume, number of standards) is made by answering questions asked by instrument. Using this approach both kinetic and single-point determinations can be carried out, and in the latter case different samples can be analysed sequentially. This paper reports the automated analysis of trypsin.     

A method for the estimation of urinary testosterone

1. A method has been developed for the estimation of testosterone in human urine by using acid hydrolysis followed by a quantitative form of a modified Girard reaction that separates a ;conjugated-ketone' fraction from a urine extract; this is followed by column chromatography on alumina and paper chromatography. 2. Comparison of methods of estimation of testosterone in the final fraction shows that estimation by gas-liquid chromatography is more reproducible than by colorimetric methods applied to the same eluates from the paper chromatogram. 3. The mean recovery of testosterone by gas-liquid chromatography is 79.5%, and this method appears to be specific for testosterone. 4. The procedure is relatively rapid. Six determinations can be performed by one worker in 2 days. 5. Results of determinations on human urine are briefly presented. In general, they are similar to earlier estimates, but the maximal values are lower.     

RAPID RELEASE OF THE ZYMOGEN GRANULE PROTEIN BY OSMIUM TETROXIDE AND ITS RETENTION DURING FIXATION BY GLUTARALDEHYDE

Fixation by osmium tetroxide and glutaraldehyde of zymogen granules isolated from rat parotid and pancreas was investigated. Protein determinations showed that osmium tetroxide caused rapid release of most of the soluble protein of the granule during fixation in buffered isotonic sucrose. Such granules when examined in the electron microscope after shadow casting appeared quite flat, indicating that most of the contents had indeed been removed. Numerous damaged membranes of the granules were also observed. In contrast, zymogen granules fixed by glutaraldehyde and shadow cast essentially retained the spherical shape and the protein contents. The application of the shadow-casting technique in quantitative studies on the protein content of zymogen granules is discussed.     

Effect of Aluminium Ions on Liposomal Membranes as Detected by Laurdan Fluorescence

We report here an investigation of the influence of aluminium on iron-induced peroxidation in brain model membranes. Laurdan fluorescence emission spectra and generalised polarisation measurements have been used to investigate how ferrous and aluminium ions can affect the phase components of phos-pholipid membranes. An increase in the generalised polarisation of oxidised liposomes with respect to controls has been observed, which reveals the presence of a less polar environment surrounding the probe that changes the properties of the bilayer.

Aluminium has been shown to facilitate iron-mediated oxidation as detected from emission fluorescence spectra. However, no quantitative influence has been calculated relative to general polarisation and derived phase state determinations. The structural influence of aluminium on membranes may therefore be less siccantly marked than initially expected.     

嵌入式AFP测试仪的设计

介绍了一个嵌入式AFP测试仪的设计。测试仪以嵌入式微处理器LPC2210为核心,主要包括数据采集、步进电机的驱动及人机交互界面等几部分。测试仪可通过RS232与PC机通讯,进行数据处理及报告分析,具有一定的临床辅助诊断价值。     

Photon correlation spectroscopy, total intensity light scattering with laser radiation, and hydrodynamic studies of a well fractionated DNA sample.

A Malvern laser light-scattering instrument has been modified for use at scattering angles down to 5° and both total intensity and quasi-elastic scattering experiments. A sample of sheared, length-fractionated calf-thymus DNA was characterized by sedimentation, viscosity and electron microscopy. Quasi-elastic scattering and absolute intensity determinations were performed with the laser instrument and intensity determinations only with a Fica conventional light-scattering photometer. The total intensity experiments gave M?_w = (3.75 ± 0.15) × 10⁶ and 〈R²〉^1/2_z = (206.9 ± 10.3) nm which yielded a value for the persistence length, allowing for polydispersity, of 66 ± 6nm. The quasi-elastic experiments at scattering angles below 20° gave D⁰_{20, w} = (2.23 ± 0.06) × 10^?8 cm²/sec which combined with S⁰_{20, w} = 15.6 in the Svedberg equation gave M?_w = (3.73 ± 0.18) × 10⁶. In addition, from the higher angle data we extracted a value of the longest intramolecular relaxation time, τ1 of 17.5 msec. This is not in particularly good agreement with τ1 predicted by the Zimm–Rouse theory using our other experimental parameters. The disagreement may be due to the restricted applicability of the Zimm–Rouse spring-bead model as a quantitative representation of DNA molecules. Alternatively, it may be due to present difficulties in the unambiguous interpretation of molecular motions from the experimental autocorrelation functions.     

Detection and discrimination of individual viruses by flow cytometry.

A new flow cytometer with a very small observation volume has been developed to detect individual viruses with good resolution, and has been used to discriminate between two types of viral particles based on differences in their light scattering. Measurements of light scattering and fluorescence made with such an instrument can provide a basis for quantitative analysis and sorting of viruses and other particles in the micron and submicron size range.     

The silica cycle during the last ice age

Qualitative and quantitative investigations of the silica geochemistry in the ocean and its cycles and changes during the Quaternary have been carried out based on more than 4000 sample determinations. The present Si cycle within the ocean balance and annual silica accumulation were determined. The main part of silica has accumulated on the ocean bottom in three silica accumulation belts: southern, equatorial and northern. The changes of the belts were synchronous for the northern and the southern hemispheres and were caused by climatic changes connected with glaciation.     

Lowry protein determination on membrane preparations: need for standardization by amino acid analysis

The protein content of three membrane protein preparations has been determined by the Lowry method with bovine serum albumin as a standard and also by quantitative amino acid analysis as an absolute method. The results differ considerably, the Lowry method giving 29–42% higher values. This implies that many published data for such proteins, based on Lowry protein determinations with bovine serum albumin as the generally applied standard, are in error. Suggestions are made on how to standardize the Lowry method so that reliable values can be obtained for membrane protein.