A Brief Review of Bone Cell Function and Importance

This review focuses on understanding the macroscopic and microscopic characteristics of bone tissue and reviews current knowledge of its physiology. It explores how these features intricately collaborate to maintain the balance between osteoblast-mediated bone formation and osteoclast-mediated bone resorption, which plays a pivotal role in shaping not only our physical framework but also overall health. In this work, a comprehensive exploration of microscopic and macroscopic features of bone tissue is presented.

Exploring the Piezoelectric Properties of Bismuth Ferrite Thin Films Using Piezoelectric Force Microscopy: A Case Study

Over recent decades, the scientific community has managed to make great progress in the theoretical investigation and practical characterization of bismuth ferrite thin films. However, there is still much work to be completed in the field of magnetic property analysis. Under a normal operational temperature, the ferroelectric properties of bismuth ferrite could overcome the magnetic properties due to the robustness of ferroelectric alignment. Therefore, investigation of the ferroelectric domain structure is crucial for functionality of any potential devices. This paper reports deposition and analyzation of bismuth ferrite thin films by Piezoresponse Force Microscopy (PFM) and XPS methods, aiming to provide a characterization of deposited thin films. In this paper, thin films of 100 nm thick bismuth ferrite material were prepared by pulsed laser deposition on multilayer substrates Pt/Ti(TiO₂)/Si. Our main purpose for the PFM investigation in this paper is to determine which magnetic pattern will be observed on Pt/Ti/Si and Pt/TiO₂/Si multilayer substrates under certain deposition parameters by utilizing the PLD method and using samples of a deposited thickness of 100 nm. It was also important to determine how strong the measured piezoelectric response will be, considering parameters mentioned previously. By establishing a clear understanding of how prepared thin films react on various biases, we have provided a foundation for future research involving the formation of piezoelectric grains, thickness-dependent domain wall formations, and the effect of the substrate topology on the magnetic properties of bismuth ferrite films.

Multiferroic/Polymer Flexible Structures Obtained by Atomic Layer Deposition

The paper considers how a film of bismuth ferrite BiFeO₃ (BFO) is formed on a polymeric flexible polyimide substrate at low temperature ALD (250 °C). Two samples of BFO/Polyimide with different thicknesses (42 nm, 77 nm) were studied. As the thickness increases, a crystalline BFO phase with magnetic and electrical properties inherent to a multiferroic is observed. An increase in the film thickness promotes clustering. The competition between the magnetic and electrical subsystems creates an anomalous behavior of the magnetization at a temperature of 200 K. This property is probably related to the multiferroic/polymer interface. This paper explores the prerequisites for the low-temperature growth of BFO films on organic materials as promising structural components for flexible and quantum electronics.

Brief Theoretical Overview of Bi-Fe-O Based Thin Films

This paper will provide a brief overview of the unique multiferroic material Bismuth ferrite (BFO). Considering that Bismuth ferrite is a unique material which possesses both ferroelectric and magnetic properties at room temperature, the uniqueness of Bismuth ferrite material will be discussed. Fundamental properties of the material including electrical and ferromagnetic properties also will be mentioned in this paper. Electrical properties include characterization of basic parameters considering the electrical resistivity and leakage current. Ferromagnetic properties involve the description of magnetic hysteresis characterization. Bismuth ferrite can be fabricated in a different form. The common forms will be mentioned and include powder, thin films and nanostructures. The most popular method of producing thin films based on BFO materials will be described and compared. Finally, the perspectives and potential applications of the material will be highlighted.

Characterization and Evaluation of Engineered Coating Techniques for Different Cutting Tools-Review

Coatings are now frequently used on cutting tool inserts in the metal production sector due to their better wear resistance and heat barrier effect. Protective hard coatings with a thickness of a few micrometers are created on cutting tools using physical or chemical vapor deposition (PVD, CVD) to increase their application performance. Different coating materials are utilized for a wide range of cutting applications, generally in bi-or multilayer stacks, and typically belong to the material classes of nitrides, carbides, carbonitrides, borides, boronitrides, or oxides. The current study examines typical hard coatings deposited by PVD and CVD in the corresponding material classes. The present state of research is reviewed, and pioneering work on this subject as well as recent results leading to the construction of complete "synthesis-structure-property-application performance" correlations of the different coatings are examined. When compared to uncoated tools, tool coatings prevent direct contact between the workpiece and the tool substrate, altering cutting temperature and machining performance. The purpose of this paper is to examine the effect of cutting-zone temperatures on multilayer coating characteristics during the metal-cutting process. Simplified summary and comparisons of various coating types on cutting tools based on distinct deposition procedures. Furthermore, existing and prospective issues for the hard coating community are discussed.

Multiferroic behavior of the functionalized surface of a flexible substrate by deposition of Bi2 O3 and Fe2 O3

Thin films of bismuth and iron oxides were obtained by atomic layer deposition (ALD) on the surface of a flexible substrate poly(4,4'-oxydiphenylene-pyromellitimide) (Kapton) at a temperature of 250°C. The layer thickness was 50 nm. The samples were examined by secondary-ion mass spectrometry, and uniform distribution of elements in the film layer was observed. Surface morphology, electrical polarization, and mechanical properties were investigated by atomic force microscope, piezoelectric force microscopy, and force modulation microscopy. The values of current in the near-surface layer varied in the range of ±80 pA when a potential of 5 V was applied. Chemical analysis was performed by X-ray photoelectron spectroscopy, where the formation of Bi₂ O₃ and Fe₂ O₃ phases, as well as intermediate phases in the Bi-Fe-O system, was observed. Magnetic measurements were carried out by a vibrating sample magnetometer that showed a ferromagnetic response. The low-temperature method of functionalization of the Kapton surface with bismuth and iron oxides will make it possible to adapt the Bi-Fe-O system to flexible electronics.

PVDF Fibers Modification by Nitrate Salts Doping

The method of inclusion of various additives into a polymer depends highly on the material in question and the desired effect. In the case of this paper, nitride salts were introduced into polyvinylidene fluoride fibers prepared by electrospinning. The resulting changes in the structural, chemical and electrical properties of the samples were observed and compared using SEM-EDX, DSC, XPS, FTIR, Raman spectroscopy and electrical measurements. The observed results displayed a grouping of parameters by electronegativity and possibly the molecular mass of the additive salts. We virtually demonstrated elimination of the presence of the γ-phase by addition of Mg(NO₃)₂, Ca(NO₃)₂, and Zn(NO₃)₂ salts. The trend of electrical properties to follow the electronegativity of the nitrate salt cation is demonstrated. The performed measurements of nitrate salt inclusions into PVDF offer a new insight into effects of previously unstudied structures of PVDF composites, opening new potential possibilities of crystalline phase control of the composite and use in further research and component design.

Characterization of GaAs Solar Cells under Supercontinuum Long-Time Illumination

This work is dedicated to the description of the degradation of GaAs solar cells under continuous laser irradiation. Constant and strong exposure of the solar cell was performed over two months. Time-dependent electrical characteristics are presented. The structure of the solar cells was studied at the first and last stages of degradation test. The data from Raman spectroscopy, reflectometry, and secondary ion mass spectrometry confirm displacement of titanium and aluminum atoms. X-ray photoelectron spectroscopy showed a slight redistribution of oxygen bonds in the anti-corrosion coating.

Piezoelectric Current Generator Based on Bismuth Ferrite Nanoparticles

Bismuth ferrite nanoparticles with an average particle diameter of 45 nm and spatial symmetry R3c were obtained by combustion of organic nitrate precursors. BiFeO₃-silicone nanocomposites with various concentrations of nanoparticles were obtained by mixing with a solution of M10 silicone. Models of piezoelectric generators were made by applying nanocomposites on a glass substrate and using aluminum foil as contacts. The thickness of the layers was about 230 μm. There was a proportional relationship between the different concentrations of nanoparticles and the detected potential. The output voltages were 0.028, 0.055, and 0.17 V with mass loads of 10, 30, and 50 mass%, respectively.

Characterization of Polyvinylidene Fluoride (PVDF) Electrospun Fibers Doped by Carbon Flakes

Polyvinylidene fluoride (PVDF) is a modern polymer material used in a wide variety of ways. Thanks to its excellent resistance to chemical or thermal degradation and low reactivity, it finds use in biology, chemistry, and electronics as well. By enriching the polymer with an easily accessible and cheap variant of graphite, it is possible to affect the ratio of crystalline phases. A correlation between the ratios of crystalline phases and different properties, like dielectric constant as well as piezo- and triboelectric properties, has been found, but the relationship between them is highly complex. These changes have been observed by a number of methods from structural, chemical and electrical points of view. Results of these methods have been documented to create a basis for further research and experimentation on the usability of this combined material in more complex structures and devices.

Surface Modification and Enhancement of Ferromagnetism in BiFeO3 Nanofilms Deposited on HOPG

BiFeO3 (BFO) films on highly oriented pyrolytic graphite (HOPG) substrate were obtained by the atomic layer deposition (ALD) method. The oxidation of HOPG leads to the formation of bubble regions creating defective regions with active centers. Chemisorption occurs at these active sites in ALD. Additionally, carbon interacts with ozone and releases carbon oxides (CO, CO2). Further annealing during the in situ XPS process up to a temperature of 923 K showed a redox reaction and the formation of oxygen vacancies (Vo) in the BFO crystal lattice. Bubble delamination creates flakes of BiFeO3-x/rGO heterostructures. Magnetic measurements (M-H) showed ferromagnetism (FM) at room temperature Ms ~ 120 emu/cm3. The contribution to magnetization is influenced by the factor of charge redistribution on Vo causing the distortion of the lattice as well as by the superstructure formed at the boundary of two phases, which causes strong hybridization due to the superexchange interaction of the BFO film with the FM sublattice of the interface region. The development of a method for obtaining multiferroic structures with high FM values (at room temperature) is promising for magnetically controlled applications.

Field Emission Properties of Polymer Graphite Tips Prepared by Membrane Electrochemical Etching

This paper investigates field emission behavior from the surface of a tip that was prepared from polymer graphite nanocomposites subjected to electrochemical etching. The essence of the tip preparation is to create a membrane of etchant over an electrode metal ring. The graphite rod acts here as an anode and immerses into the membrane filled with alkali etchant. After the etching process, the tip is cleaned and analyzed by Raman spectroscopy, investigating the chemical composition of the tip. The topography information is obtained using the Scanning Electron Microscopy and by Field Emission Microscopy. The evaluation and characterization of field emission behavior is performed at ultra-high vacuum conditions using the Field Emission Microscopy where both the field electron emission pattern projected on the screen and current–voltage characteristics are recorded. The latter is an essential tool that is used both for the imaging of the tip surfaces by electrons that are emitted toward the screen, as well as a tool for measuring current–voltage characteristics that are the input to test field emission orthodoxy.

Scanning electron microscopy and energy-dispersive X-ray spectroscopy analysis of electrochemically etched graphite tips created from pencil lead

Modern day pencil lead is a material of many possibilities. Manufacture process is fast, easy, and well established, yet the full potential of its use still remains to be uncovered. Graphite content ratio to binding clays determines basic properties of the lead like its toughness and color, but more interesting qualities like conductivity and reactivity as well. Properly employed electrochemical etching with a bubble membrane creates sharp and smooth graphite tips, which can be, given enough graphite content, used as probes in several measurement techniques. Observing and adjusting the tip creation process and the results for use in further research are the objectives of this paper.

Morphological features in aluminum nitride epilayers prepared by magnetron sputtering

The aim of this study is to characterize the surface topography of aluminum nitride (AlN) epilayers prepared by magnetron sputtering using the surface statistical parameters, according to ISO 25178-2:2012. To understand the effect of temperature on the epilayer structure, the surface topography was investigated through atomic force microscopy (AFM). AFM data and analysis of surface statistical parameters indicated the dependence of morphology of the epilayers on their growth conditions. The surface statistical parameters provide important information about surface texture and are useful for manufacturers in developing AlN thin films with improved surface characteristics. These results are also important for understanding the nanoscale phenomena at the contacts between rough surfaces, such as the area of contact, the interfacial separation, and the adhesive and frictional properties.

Relevance of the light line in planar photonic crystal waveguides with weak vertical confinement

The concept of the so-called light line is a useful tool to distinguish between guided and non-guided modes in dielectric slab waveguides. Also for more complicated structures with 2D mode confinement, the light lines can often be used to divide a dispersion diagram into a region of a non-guided continuum of modes, a region of discrete guided modes and a forbidden region, where no propagating modes can exist. However, whether or not the light line is a concept of practical relevance depends on the geometry of the structure. This fact is sometimes ignored. For instance, in the literature on photonic crystal waveguides, it is often argued that substrate-type photonic crystal waveguides with a weak vertical confinement are inherently lossy, since the entire bandgap including the line defect modes is typically located above the light line of the substrate. The purpose of this article is to illustrate that this argument is inaccurate and to provide guidelines on how an improved light line concept can be constructed.

Core-shell La(1-x)Sr(x)MnO3 nanoparticles as colloidal mediators for magnetic fluid hyperthermia

Core-shell nanoparticles consisting of La(0.75)Sr(0.25)MnO(3) cores covered by silica were synthesized by a procedure consisting of several steps, including the sol-gel method in the presence of citric acid and ethylene glycol, thermal and mechanical treatment, encapsulation employing tetraethoxysilane and final separation by centrifugation in order to get the required size fraction. Morphological studies revealed well-separated particles that form a stable water suspension. Magnetic studies include magnetization measurements and investigation of the ferromagnetic-superparamagnetic-paramagnetic transition. Magnetic heating experiments in 'calorimetric mode' were used to determine the heating efficiency of the particles in water suspension and further employed for biological studies of extracellular and intracellular effects analysed by tests of viability.

Silica encapsulated manganese perovskite nanoparticles for magnetically induced hyperthermia without the risk of overheating

Nanoparticles of manganese perovskite of the composition La(0.75)Sr(0.25)MnO(3) uniformly coated with silica were prepared by encapsulation of the magnetic cores (mean crystallite size 24 nm) using tetraethoxysilane followed by fractionation. The resulting hybrid particles form a stable suspension in an aqueous environment at physiological pH and possess a narrow hydrodynamic size distribution. Both calorimetric heating experiments and direct measurements of hysteresis loops in the alternating field revealed high specific power losses, further enhanced by the encapsulation procedure in the case of the coated particles. The corresponding results are discussed on the basis of complex characterization of the particles and especially detailed magnetic measurements. Moreover, the Curie temperature (335 K) of the selected magnetic cores resolves the risk of local overheating during hyperthermia treatment.

Positive and negative regulation of myogenic differentiation of C2C12 cells by isoforms of the multiple homeodomain zinc finger transcription factor ATBF1

The ATBF1 gene encodes two protein isoforms, the 404-kDa ATBF1-A, possessing four homeodomains and 23 zinc fingers, and the 306-kDa ATBF1-B, lacking a 920-amino acid N-terminal region of ATBF1-A which contains 5 zinc fingers. In vitro, ATBF1-A was expressed in proliferating C2C12 myoblasts, but its expression levels decreased upon induction of myogenic differentiation in low serum medium. Forced expression of ATBF1-A in C2C12 cells resulted in repression of MyoD and myogenin expression and elevation of Id3 and cyclin D1 expression, leading to inhibition of myogenic differentiation in low serum. In contrast, transfection of C2C12 cells with the ATBF1-B isoform led to an acceleration of myogenic differentiation, as indicated by an earlier onset of myosin heavy chain expression and formation of a higher percentage of multinucleated myotubes. The fourth homeodomain of ATBF1-A bound to an AT-rich element adjacent to the E1 E-box of the muscle regulatory factor 4 promoter mediating transcriptional repression. The ATBF1-A-specific N-terminal region possesses general transcription repressor activity. These results suggest that ATBF1-A plays a role in the maintenance of the undifferentiated myoblast state, and its down-regulation is a prerequisite to initiate terminal differentiation of C2C12 cells.

Myb-interacting protein, ATBF1, represses transcriptional activity of Myb oncoprotein

Using the yeast two-hybrid system, the transcription factor ATBF1 was identified as v-Myb- and c-Myb-binding protein. Deletion mutagenesis revealed amino acids 2484-2520 in human ATBF1 and 279-300 in v-Myb as regions required for in vitro binding of both proteins. Further experiments identified leucines Leu325 and Leu332 of the Myb leucine zipper motif as additional amino acid residues important for efficient ATBF1-Myb interaction in vitro. In co-transfection experiments, the full-length ATBF1 was found to form in vivo complexes with v-Myb and inhibit v-Myb transcriptional activity. Both ATBF1 2484-2520 and Myb 279-300 regions were required for the inhibitory effect. Finally, the chicken ATBF1 was identified, showing high degree of amino acid sequence homology with human and murine proteins. Our data reveal Myb proteins as the first ATBF1 partners detected so far and identify amino acids 279-300 in v-Myb as a novel protein-protein interaction interface through which Myb transcriptional activity can be regulated.

Identification of CpG island at the 5' end of murine leukemia inhibitory factor gene

We identified a CpG island at the 5' end of murine leukemia inhibitory factor gene (LIF). The CpG island is 0.6 kb long and covers most of the first exon and first intron. The region is non-methylated, its G+C content is 65% and relative frequency of CpG dinucleotide is 0.7. The block of 150 nucleotides, which is 72% conserved between murine, human, ovine and porcine genes, is a part of the CpG island. Two DNA fragments from this CpG island interact with nuclear proteins from NIH 3T3 cells. One fragment partially covers the block of conserved nucleotides. Human, ovine and porcine LIF genes also contain G+C- and CpG-rich sequences in the corresponding region.

Blastocyst implantation depends on maternal expression of leukaemia inhibitory factor

A critical point during mammalian pregnancy is the implantation of the blastocyst when the embryo attaches to the wall of the uterus. The autonomously developing preimplantation embryo then becomes dependent on the maternal environment for its continued development. Little is known about the regulation of implantation, except that a complex interaction between peptide and steroid hormones synchronizes the preparation of the uterus for implantation with the development of the embryo. Whether the implantation event is under maternal or embryonic control is also unclear (reviewed in refs 1, 2). We have previously shown that a cytokine, leukaemia inhibitory factor (LIF), is expressed in the uterine endometrial glands specifically on the fourth day of pregnancy. This burst of expression is under maternal control and always precedes implantation of the blastocyst. Here we report that transient expression of LIF in mice is essential for implantation. Females lacking a functional LIF gene are fertile, but their blastocysts fail to implant and do not develop. The blastocysts, however, are viable and, when transferred to wild-type pseudopregnant recipients, they can implant and develop to term.

Evaluation of a simple screening test for the quality of drinking water systems

A simple and inexpensive assay for detection of H2S producing bacteria in drinking water was evaluated in Paraguay. Using an improved preparation procedure, results were basically temperature independent in the range of 22-37 degrees C and correlated well with the presence of total coliform bacteria (96%, 28 degrees C). The assay was not suitable for control of surface water and dug well water due to the frequent presence of non-faecal coliforms. However, it was very suitable for routine control of high quality water systems, like treated community water systems or deep-tube well water, where complete absence of coliforms is required. The H2S-test is very inexpensive and does not require a laboratory technician or special equipment. Its use permits a cost-effective routine control of high quality community water systems in developing countries. In addition, this test turned out to be an effective educational tool for heightening the awareness of people towards dangers of unclean drinking water.

[Carotenemia]

The authors demonstrate two infants with a yellow skin coloration which developed as a result of excessive dietary carotenoid intake. The yellow coloration, contrary to jaundice, did not affect the sclerae. Elevated blood carotenoid levels were found and a temporary increase of aminotransferases. In both infants lower IgA levels were recorded. After modification of the diet the yellow coloration disappeared and gradually the aminotransferases reached normal levels.

[Analysis of respiratory mechanics in fiberoptic bronchoscopy in healthy probands and patients]

The airway resistance was measured via oscillation in 30 patients during routine bronchoscopy. In 10 healthy subjects body plethysmographic measurements were done during fiberoptic bronchoscopy. It was found that fiberoptic bronchoscopy results in an only slight, but significant increase in airway resistance. The Raw rose from an average of 1.94 to 3.04 mbar/l/s.

[Effect of nifedipine alone and in combination with salbutamol on the beat frequency of human nasal cilia]

In 25 patients suffering from chronic obstructive bronchitis, it has been shown that the administration of nifedipine brings about a decrease in the beat rate of nasal cilia which, in the individual case, may be very marked. The addition of salbutamol can more than compensate for this decrease in cilial beat rate.

An improved double stranded DNA sequencing method using gene 32 protein

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Expression and properties of prochymosin derivatives containing extensions of various length in the pro-part

A series of hybrid prochymosin derivatives containing portions of the simian virus 40 small-t antigen in the pro-part was constructed. Portions comprising 93, 63, 47, 12, and 1 amino acid (aa) from the N terminus of the small-t antigen were separately fused via eight polylinker-encoded amino acids to a prochymosin product commencing with the 5th aa of the pro-part. All the DNAs coding for the hybrid proteins were put under pL-promoter control in the expression constructs. Expression revealed that only fusion of the 47-aa or 12-aa stretch of the small-t antigen to prochymosin gave stable protein products and that only the latter one allowed the hybrid prochymosin to be activated to chymosin. The products containing 93 aa and 63 aa of small-t antigen were unstable and degraded. Complete removal of the small-t antigen portion led to mRNA instability, probably owing to inefficient initiation of translation.

Application of sandwich immunoassays for the determination of sample-specific background signals and its use for calibration of immunoassays

Sample-related background signals in immunoassays can be measured by a variation of the double antibody sandwich principle, in which the unlabelled specific antibody is substituted by a similar unrelated non-specific antibody. This permits differentiation between the analyte-specific and the background signal components for each sample. The method permits selection of sera with no or low analyte content for use as analyte diluent and for defining the zero point of the calibration curve. The method also permits control of analyte content during production processes which may change the background signal as well as identification of samples with atypical background signals. The procedure has been used for the calibration of enzyme immunoassays for alpha-fetoprotein (AFP) and human thyroid-stimulating hormone (TSH).

An enzymatic method for calibration of serum lipase assays

An enzymatic method for the calibration of a turbidimetric lipase assay is described, based on measurement of free fatty acids liberated by the action of lipase. The substrate of the turbidimetric assay is a colipase-containing triolein emulsion. For determination of the free fatty acids a commercial test kit including acyl-CoA synthetase, acyl-CoA oxidase, and peroxidase is used. Intra- and interassay imprecision (CV) is about 5% at above-normal lipase activities, about 10% at normal values. Temperature coefficients are 1.24 and 1.45, respectively, for measurements at 30 and 37 degrees C vs 25 degrees C.

An enzymatic method for calibration of serum lipase assays

An enzymatic method for the calibration of a turbidimetric lipase assay is described, based on measurement of free fatty acids liberated by the action of lipase. The substrate of the turbidimetric assay is a colipase-containing triolein emulsion. For determination of the free fatty acids a commercial test kit including acyl-CoA synthetase, acyl-CoA oxidase, and peroxidase is used. Intra- and interassay imprecision (CV) is about 5% at above-normal lipase activities, about 10% at normal values. Temperature coefficients are 1.24 and 1.45, respectively, for measurements at 30 and 37 degrees C vs 25 degrees C.

Comparison of the effects of sequential or simultaneous administration of salbutamol and beclomethasone dipropionate

The effect of the simultaneous administration of salbutamol and beclomethasone dipropionate, from a combination inhaler, was compared with the same doses given with an interval of 10 min, from separate inhalers, in a group of 40 asthmatic females. The double-blind parallel-group study was well balanced and lasted 4 weeks. Both groups showed a similar improvement in thrice-weekly lung function values and daily symptoms in week 4 compared to week 1. There were no other differences and no adverse reactions. The combination inhaler is a useful alternative for maintenance treatment in patients who require an inhaled steroid.

Shielding effects at 17 alpha-substituted estrogens. A tentative explanation for the low biological activity of 17 alpha-ethyl-estradiol based on i.r. and NMR spectroscopic studies

Infrared data of the hydroxyl stretching band and NMR data of the hydroxyl proton for 7 different 17-substituted estradiol-3-methyl-ether compounds have been recorded. The band positions can be related to the extent of shielding effects or intramolecular interactions of hydrogen bonding type. The splitting of several i.r. bands can be explained on the basis of rotamers and restrictions in the free rotation of the hydroxyl group. This holds especially for 17 alpha-ethyl-estradiol, in which the access to the free electron pairs of the OH group is hindered by the 17 alpha-ethyl group. This may explain the very low receptor binding and reduced biological activity of 17 alpha-ethyl-estradiol in contrast to the stronger binding of 17 alpha-methyl-, 17 alpha-vinyl or 17 alpha-ethinyl-estradiol.

Steroid binding to the cytosolic estrogen receptor from rat uterus. Influence of the orientation of substituents in the 17-position of the 8 beta- and 8 alpha-series

The exact chemical and sterical requirements in the 17-position of 8 beta- and 8 alpha-estrogens for an effective binding to the cytosolic receptor of immature rat uterus were investigated by competition experiments under non-equilibrium conditions. Oxygen or nitrogen functions with free electron pairs seem to be of essential importance in the 17-position. In contrast to 17 alpha-methyl-, -vinyl- or -ethinyl-substituents a 17 alpha-ethyl group strongly disturbs receptor binding. Also the introduction of a quasi equatorial allene or a 17 beta-ethinyl group reduces receptor binding. In comparison to the 8 beta-estrogens, the 8 alpha-derivatives always showed lower, but still significant receptor binding and similar response to changes of substituents in the 17-position.

The distribution of chymotrypsin within the feces and description of a new device for the preparation of stool samples

We measured the distribution of chymotrypsin within feces by comparing duplicate 100-mg stool aliquots from 48 stool specimens. For practical purposes, the distribution of the enzyme in stool appears sufficiently homogeneous to assure representative results even from 100-mg stool aliquots. Given this likelihood, we have developed a new disposable device that measures 100-mg stool aliquots hygienically, prepares this material for shipping by mail, homogenizes and suspends the stool sample, and facilitates centrifugation of the fecal suspension, all within the same instrument. Performance studies with this new device revealed that stools of different consistency can be measured out precisely and conveniently by volume. The difference in the specific weight of different stools appears to be so low that for practical purposes a 100-mg mass of stool can be weighed out by volume.

New photometric assay for chymotrypsin in stool

In this new photometric assay fecal samples are pretreated with detergent and high concentrations of salts. The subsequent kinetic enzyme determination step involves the chromogenic substrate succinyl-Ala-Ala-Pro-Phe-4-nitroanilide. The sample pretreatment assures a nearly complete solubilization of the formerly particle-bound enzyme, thus permitting determination of the enzyme activity in either the suspension or the supernate after centrifugation. Furthermore this pretreatment enhances the enzyme activity and decreases the Km value. Results by this assay correlate well with those by classical titrimetry and the method is easily adapted to automated systems.

New photometric assay for chymotrypsin in stool

In this new photometric assay fecal samples are pretreated with detergent and high concentrations of salts. The subsequent kinetic enzyme determination step involves the chromogenic substrate succinyl-Ala-Ala-Pro-Phe-4-nitroanilide. The sample pretreatment assures a nearly complete solubilization of the formerly particle-bound enzyme, thus permitting determination of the enzyme activity in either the suspension or the supernate after centrifugation. Furthermore this pretreatment enhances the enzyme activity and decreases the Km value. Results by this assay correlate well with those by classical titrimetry and the method is easily adapted to automated systems.

The distribution of chymotrypsin within the feces and description of a new device for the preparation of stool samples

We measured the distribution of chymotrypsin within feces by comparing duplicate 100-mg stool aliquots from 48 stool specimens. For practical purposes, the distribution of the enzyme in stool appears sufficiently homogeneous to assure representative results even from 100-mg stool aliquots. Given this likelihood, we have developed a new disposable device that measures 100-mg stool aliquots hygienically, prepares this material for shipping by mail, homogenizes and suspends the stool sample, and facilitates centrifugation of the fecal suspension, all within the same instrument. Performance studies with this new device revealed that stools of different consistency can be measured out precisely and conveniently by volume. The difference in the specific weight of different stools appears to be so low that for practical purposes a 100-mg mass of stool can be weighed out by volume.

Stable nitrones from 17 beta-Hydroxylamine derivatives of 8 beta- and 8 alpha-estrone

17 beta-Hydroxylamine derivatives of 8 beta and 8 alpha-estrone can be obtained by reduction of the corresponding oximes with diborane or NaCNBH3. The products can be converted easily and reversibly to nitrones by addition of aldehydes or ketones. The nitrones are more stable than the corresponding hydroxylamines, and may be used as protecting groups.