bluuebunny/crossref_metadata_2025 huggingface dataset:
On the thermal ignition of combustible materials
Authors: Mikkola Esko , Wichman Indrek S.
Published: May 2005

Formulas are derived for the time to achieve the ignition temperature as a function of the incident heat flux and the various thermophysical material parameters for thermally thick, thermally thin and thermally intermediate solid combustibles. Predictions are compared with recent experimental data for various natural wood species and wood products, and to previous data for wood and thermoplastics. The correlations are excellent when (1) the physical parameters used as the axes of the plots are chosen consistent with those of the theoretical formulas and (2) the experiments and the materials do not violate any of the restrictions imposed by the theory. From these plots it is easy to estimate the minimum heat flux for ignition, which is of great importance both in practice and for making theoretical predictions.
An examination of piloted ignition characteristics of cellulosic materials using the ISO ignitability test
Authors: Toal B. R. , Silcock G. W. H. , Shields T. J.
Published: May 2005

The ISO Ignitability Test apparatus is used to determine the times to ignition for cellulosic materials under an incident radiative flux within the range 1‐‐5 kW/m2. A linear relationship is determined between time to ignition and incident flux, and a means of using these results to classify building materials is proposed, based upon an empirical flux‐time product.
Long‐term reproducibility of small‐scale tests used for measuring the flammability of conveyor belting
Authors: Mintz K. J.
Published: May 2005

Three small‐scale flammability tests were evaluated for potential use in quality control. The small‐scale flame test produced excessive scatter of data, the hot‐plate ignition test gave reasonably reproducible data, but the critical oxygen index yielded superior results and is recommended for quality control testing.
Combustibility of building materials
Authors: Richardson Leslie R. , Brooks Mary E.
Published: May 2005

Until the 1960s ASTM E136 and CAN/ULC‐S114 test methods were adequate for determination of non‐combustibility in materials being used to construct most buildings. However, since then there has been a very large increase in the use of products that are considered safe for construction of buildings required to be noncombustible but which are classified as combustible by these simple pass/fail tests. Therefore, Forintek Canada Corp. have developed an approach to define the combustibility of these new materials, based upon their release of heat when tested using the ASTM E1354 cone calorimeter.
Surface parameters from small‐scale experiments used for measuring HCl transport and decay in fire atmospheres
Authors: Galloway F. M. , Hirschler M. M. , Smith G. F.
Published: May 2005

The decay of HCl was investigated in two small‐scale scenarios: pure HCl injection into a 31 chamber and combustion of plasticized PVC in a 2001 chamber. The effects investigated included (1) humidity, (2) temperature, (3) concentration of HCl and (4) wall material. Surface materials studied were PMMA, ceiling tile (front and back), Marinite, painted PMMA, unpainted gypsum board and cement. In view of the very rapid HCl decay in most of those surfaces, the effects were often examined with small ‘chips’ of materials in a PMMA chamber, with fresh walls for each experiment. Experiments were also carried out to investigate the effect of surface ageing, with painted gypsum board, painted PMMA and unpainted gypsum board walls. HCl decay is very fast in cement or unpainted gypsum board surface (almost impossible to saturate with HCl) and almost as fast on ceiling tile and Marinite. Saturation of HCl can be reached on painted gypsum board and painted PMMA surfaces, albeit at different rates. An earlier empirical model from mathematical fitting had been followed by a new HCl generation, transport and decay model, with a sound physical basis. This allowed calculations of parameters for all the surfaces used. Much work has already been done in devising and writing a zone model for use together with fire hazard models (particularly the NIST model, FAST) to calculate correct HCL concentrations in various fire scenarios. This work, which concludes the investigation of these two static fire scenarios for the surfaces analysed, represents one more step in the pursuit of that goal.
Effect of orientation on burning rate of solid combustible
Authors: Ohtani H. , Ohta K. , Uehara Y.
Published: May 2005

The effect of orientation on the combustion phenomena of a PMMA plate was studied experimentally. A PMMA plate was held by a sample holder made of insulation boards with only one face exposed to the air. Observation of burning inclined plates revealed that flame shape varied with inclination angle. The burning behavior of the upper surface of an inclined plate appeared to differ from that of the lower surface. However, the surface regression rate was found to depend on the inclination angle from the vertical plane. This rate for the upper surface was identical to that of the lower one if the absolute value of the inclination angle was identical, and was found to depend on empirical relationships involving natural convective heat transfer around a heated plate.
Note: Effect of some zinc chelates on the flammability and thermal behaviour of polypropylene
Authors: Gad A. M. , Khattab M. A. , Kandil S. H. , Dawoud A. F. , Soliman A. A. , El‐Sharkawy M. H.
Published: May 2005

Some zinc chelates were prepared according to conventional methods, and were mixed with polypropylene in the presence and absence of a halogenated compound (Cereclor 70). The effect of these chelates on the flammability and thermal behaviour of polypropylene was studied by measuring the limiting oxygen index values and by the use of thermal analysis. This results showed that these chelates are ineffective in reducing the flammability of polypropylene but their effectiveness is enhanced to varying extents by the addition of Cereclor.
The effects of geometry and ignition mode on ignition times obtained using a cone calorimeter and ISO ignitability apparatus
Authors: Shields T. J. , Silcock G. W. , Murray J. J.
Published: May 2005

Three timber‐based materials were investigated by subjecting them to a constant uniform heat flux in the range 20–70 kW m−2 using a Cone Calorimeter and the ISO Ignitability Apparatus. The specimens were examined in the vertical and horizontal orientations in the Cone Calorimeter using gas flame pilot, spark pilot and spontaneous methods of ignition. They were also studied using the ISO Ignitability Apparatus in the normal and inverted horizontal orientations using gas flame pilot and spontaneous methods of ignition. The results obtained are compared by specimen, orientation and mode of ignition.
Flame‐retardant treatment of some tropical timbers
Authors: Eboatu A. N. , Garba B. , Akpabio I. O.
Published: May 2005

The Superphosphate Fertilizer, to be referred to simply as fertilizer, was used to impregnate some tropical timbers. It was observed that this treatment drastically altered the thermal characteristics of these materials. The results are interpreted as arising from the fact that on heating, fertilizer evolves molecules that interfere with the chemistry of pyrolysis/combustion of wood cellulose.
Smoke development and engineering aspects of smoke‐extraction systems for atria in Hong Kong
Authors: Chow W. K.
Published: May 2005

The smoke‐filling process in an atrium is studied in this paper using the plume equation of Thomas et al. A time constant is proposed to describe the smoke‐filling time of the atrium space. This parameter is recommended to be used as a guideline for local projects in determining whether a smoke‐extraction system has to be installed. Finally, the engineering aspects to be noted in designing smoke‐extraction systems for an atrium space are introduced.
Comparison of the smoke toxicity of four vinyl wire and cable compounds using different test methods
Authors: Hirschler Marcelo M. , Grand Arthur F.
Published: May 2005

Four vinyl wire and cable materials were tested using five smoke toxic potency test methods: the NBS cup furnace test (in its flaming and non‐flaming modes), the NIST radiant test, the NIBS IT50test (also using the radiant apparatus) and the UPITT test. One of the materials is a standard poly(vinyl chloride) (PVC) flexible wire and cable material, used commercially for wire insulation. The three other materials tested represent a new family of vinyl thermoplastic elastomer alloys, which are advanced materials with good fire performance, particularly in terms of heat release and smoke obscuration. It was found that the smokes from all four materials are similar in terms of their toxic potencies, and that they are all within the ‘common’ range of toxic potency found. In particular, the toxic potencies of the smoke from the new vinyl thermoplastic elastomer alloys are not significantly different from those of other traditional vinyl wire and cable compounds. The results of the tests were also interpreted in terms of the toxicities and concentrations of the individual gases emitted. The fractional effective dose of the toxicants analysed was sufficient to account for the toxicity of the smoke for the NBS cup furnace and the NISt radiant test. It was not able to account for the toxicity found in the UPITT test. The adequacy of the test protocols themselves was also investigated. It was found that the UPITT and the NIBS IT50method are inadequate for measurement of smoke toxicity. It was also found that the NIST radiant test protocol is the one most likely to lead to the smallest amount of future testing.
One‐ and two‐sided burning of thermally thin materials
Authors: Ohlemiller T. , Shields J.
Published: May 2005

The rate of heat release from a thermally thin material burning on both sides will be more than twice the value seen when only one side is burning. Two simplified models demonstrate that this is a consequence of the Arrhenius temperature dependence of the gasification rate of the solid. Experiments carried out on three composite materials over a range of incident heat fluxes confirm this effect. It is inferred that a further consequence of this heat release enhancement is an increased tendency for concurrent flame spread in the two‐sided burning case. Materials whose application could lead to two‐sided burning should thus be assessed in this mode to obtain a true picture of their flammability potential.
Note: Fire test data available for your purpose
Authors: Opstad Kristen , Lønvik Lars Einar
Published: May 2005

The EUREFIC (European Reaction to Fire Classification) has produced many fire test data made available through a Data Converting System (DCS). DCS is a simple PC‐based program which transfers data logger files into a standard fire test data format, given by FDMS (Fire Data Management System). DCS is also capable of transferring standard data files into data formats of common spreadsheets. The EUREFIC programme has made two models for assessing large‐scale performance of test materials. These models are integrated into a PC program called CT (Cone Tools).
The study and application of LL flame retardant
Authors: Wenqing Qin , Feng Li
Published: May 2005

Inorganic flame retardants containing water are less likely to produce toxic gases and smoke during combustion. The raw materials used to synthesize inorganic flame retardants are inexpensive and readily available. Therefore it is appropriate to research and synthesize these kinds of flame retardants and use them to produce building materials that have improved flame retardance and a low price and that constitute no environmental hazards. This paper introduces one kind of liquid,‘LL flame retardant’, which is the product of the reaction of phosphoric acid and aluminium hydroxide under specified reaction conditions. This flame retardant can be used for fire‐retardant coating and can also treat the combustible materials, such as fabrics, paper and wood. This paper describes the preparations, properties and the mechanism of flame‐retardant action of this additive.
Rate of heat release and ignitability indices for surface linings
Authors: Kokkala Matti A. , Thomas Philip H. , Karlsson Björn
Published: May 2005

Dimensional analysis is applied to one form of fire growth in a compartment to derive two indices for the classification of linings, an ignitability index and a rate of heat release index, that can be combined into a fire growth parameter, which here is made proportional to the time to flashover in the internationally standardized Room/Corner Test. The ignitability index is the inverse of the time to ignition. The rate of heat release index is obtained by integrating the rate of heat release in time, weighted in such a way that the values of rate of heat release immediately after ignition are of higher importance than those at later times. Both indices are determined from test results of the Cone Calorimeter.
Urinary phenylethylamine excretion in phobic and obsessive patients
Authors: Theofilopoulos N. , Flaskos J. , George A. J.
Published: May 2005

Urinary excretion of phenylethylamine (PEA) was determined in 19 agoraphobic, 15 obsessive compulsive and 10 neurotic depressive outpatients, and 17 healthy volunteers. Variations in urinary PEA concentrations did not appear to correlate with any of the diagnostic groups.
Intermittent micromotion and polyethylene particles inhibit bone ingrowth into titanium chambers in rabbits
Authors: Goodman Stuart B. , Aspenberg Per , Song Yong , Regula Donald , Lidgren Lars
Published: May 2005

We performed a histomorphological and morphometric analysis of the effects of short daily periods of micromotion and phagocytosable particles of high density polyethylene (PE) on bone ingrowth into a 1 × 1 × 5 mm canal within a titanium chamber in rabbits. The micromotion chamber (MC) was implanted in the tibia of nine mature New Zealand white rabbits. After osseointegration and first harvest of tissue, 40 micromotions (amplitude = 0.5 mm) were applied daily at a rate of 1 Hz for a 3‐week period. The tissue within the chamber was then harvested. For the second treatment, PE particles (108/mL) were placed within the canal. The tissue in the chamber was harvested 3 weeks later. The next treatment was a 3‐week rest period, in which neither micromotion nor particles were utilized; a harvest followed. The final treatment combined PE particles and micromotion, followed by a harvest 3 weeks later. Sections from control harvests contained extensive trabecular bone arranged longitudinally throughout the canal in a fibrovascular stroma. Micromotion produced longitudinally oriented fibrous tissue within the chamber. PE particles were associated with macrophages, surrounding and engulfing the birefringent particles. The combination of particles and micromotion produced a fibrous stroma laden with macrophages. PE particles and micromotion, alone or together, produced a similar effect in inhibiting bone ingrowth, compared to nonmoved chambers without particles. In this short‐term experiment, no additive or potentiating effect of these two stimuli could be demonstrated. © 1995 John Wiley & Sons, Inc.
The separation of flour into fractions of different protein contents by means of air classification
Authors: Jones C. R. , Halton P. , Stevens D. J.
Published: May 2005

Fractions of markedly different protein contents may be obtained by air‐classifying flour (in the sub‐sieve range) at cut sizes of about 17 and 35 μ respectively. Of these fractions, the fine, 1 (of high protein content), contains fragments of interstitial endosperm protein and small starch granules; the intermediate, 2 (low protein), mainly large starch granules; the coarse, 3, fragments of endosperm cells. The yields and protein contents of the fractions vary with different wheats; the yields of 1 and 2 may be greatly increased through suitably grinding the flour after milling.

In general, 1 may be used for raising the protein content of flours deficient in protein to a level suitable for bread‐making. The amount of 1 required depends on its protein contents and on whether it came from a hard or soft wheat, the hard wheat fraction having better bread‐making qualities. The resulting variation in the proportion of 1 required in the blend causes variation in the proportion of other particulate materials introduced with 1, in which they have become concentrated during the air classification. These include diastatically active agents and finely divided discolouring matter; the level of the former reached in the blend greatly affects its bread‐making value. Pre‐grinding of the flour may be helpful in this respect.

When chlorinated, 2 is potentially useful for making light‐structured cakes, but hard English wheats have mainly given less satisfactory results than soft. Under certain conditions, 3, with or without 2, may be better for biscuit‐making than the parent flour.
Problems in large‐scale culture of H. pertussis
Authors: Billaudelle H. , Hedén C.‐G. , Malmgren B.
Published: May 2005

A study of factors affecting the reproducibility and yields in cultivations of H. pertussis (the whooping cough organism). The search for suitable media led to the development of a new kind of blood medium suitable for pre‐cultures. Sterility of the blood additive could be ensured by filtration, and contamination on starting the freeze‐dried cells was avoided by the use of a special kind of ampoule.

In the course of studies of different cultivation techniques a 6,000 ml ‘pulsaerator’ was found to be ideal for the preparation of ordinary small batches. Inoculation density, aeration and other factors affecting the yield were studied and a culture cycle suitable for preparing 500 l. batches was developed.
Separation of acid polyelectrolytes and proteins in cellular extracts—I
Authors: Hammarsten E. , Palmstierna H. , Meyer E.
Published: May 2005

An electrophoretic method for the separation of acid polyelectrolytes from proteins in cell extracts is described.

A description of the apparatus is given and some results of the separation of extracts from Bordetella pertussis are included.
Distribution of bacterial cells within fibrous air sterilization filters
Authors: Aiba Shuichi , Kodama Tohru , Sakamoto Hideo
Published: May 2005

Probability theory has been applied to the analysis of bacterial distribution within a fibrous air sterilization filter. For a long filter layer, to which the so‐called ‘log‐penetration’ law is no longer applicable, the probability theory is considered to be effective in interpreting the distribution data.

The effects of the diameter, volume fraction and moisture content of the glass‐fibre on the longitudinal distribution of bacterial cells, were studied. The distribution was estimated beyond the experimental data points. This estimation will be of use for predicting the ‘life’ of an air sterilization filter.
The effect of agitation on the rate of acid formation byLactobacillus delbrueckii
Authors: Kempe Lloyd L. , West Ronald E.
Published: May 2005

The effect of agitation on the rate of acid formation by the microaerophilic organismLactobacillus delbrueckiiwas studied. Fermentations were conducted at constant temperature and pH, and with the continuous addition of a nutrilite source. The range of agitator speeds was from 85 to 720 rev/min.

The acid formation rate was found to increase with increasing agitator speeds and decrease with decreasing speeds if corn‐steep liquor was the nutrilite source. No effect of agitation was observed with yeast extract as the nutrilite source.

The data from corn‐steep liquor media were found to be consistent with a mass transfer mechanism, but did not warrant a conclusion as to the specific nature of the effect of agitation. It was concluded, however, that the effect of agitation on the acid formation rate was at most very small.
Glycerol production: A pilot‐plant investigation for continuous fermentation and recovery
Authors: Harris John F. , Hajny George J.
Published: May 2005

A pilot plant was built to evaluate the economic potentialities of producing glycerol from sugar by the bisulphite fermentation process. The design of this small unit was based on information collected from bench‐scale studies of the fermentation and recovery processes taking advantage of new separation techniques.

A beer containing 5 per cent of glycerol is produced in a continuous fermentation in which the free bisulphite level is automatically controlled. The effluent from the fermentor is centrifuged, and the yeast is returned to the fermentation. The dilute clarified beer is acidified; sulphur dioxide, acetaldehyde, and alcohol are removed; and the stripped solution is neutralized and concentrated until it contains 45 per cent of glycerol. This concentrated glycerol stock is purified by using a combination of ion‐exclusion and ion‐exchange.

Good fermentation control results in a beer that has a low solids–to–glycerol ratio, low organic acid content, and low residual sugar. The method of glycerol purification results in a high glycerol recovery, since no distillation of glycerol is involved. The sulphur dioxide removed from the beer is recycled through the fermentation so that the chief raw materials used in the process are sugar, sulphuric acid, and sodium carbonate. The yields of products based on sugar charged are: glycerol, 25 per cent; alcohol, 17 per cent; and acetaldehyde, 11 per cent.

The economic success of the process depends to a large extent upon the price of sugar. Under present conditions it is felt that the process is competitive.
Disruption of frozen bacteria as a consequence of changes in the crystal structure of ice
Authors: Edebo L. , Hedén C.‐G.
Published: May 2005

It is shown that at −25°C alterations in the crystal structure of ice caused by repeated pressure changes in the regions of 2000 and 3500 kg/cm2 are accompanied by a disruption of E. coli cells suspended in the ice.
Continuous culture experiments with saccharomyces rouxii
Authors: Dawson P. S. S.
Published: May 2005

Growth of Saccharomyces rouxii, an osmophilic yeast that produces glycerol and arabitol, was investigated using chemically defined media in continuous culture. Total polyol production increased with increasing aeration and growth rate. At very low aeration levels ethanol was produced but as aeration levels were increased ethanol could not be detected, formation of d‐arabitol remained constant and formation of glycerol increased.

In fully aerobic cultures with a replacement time of twelve hours, nitrogen‐limited growth resulted in accumulation of glycerol in the medium. In glucose‐limited growth glycerol tended to decrease. It was probably metabolized as a secondary carbon source. The optimum temperature for polyol production was 30°C while that for cell growth was 27°C.
Submerged growth of cells of higher plants
Authors: Nickell Louis G. , Tulecke Walter
Published: May 2005

The submerged propagation of plant tissue and cell cultures has now reached the stage where mass amounts of material can be produced. In discussing these advances, various aspects of the technology involved are discussed: the methods of isolation and establishment of cultures, the media used for culture and their effects on growth, the systems used for growth and a comparison of their effectiveness.

Biochemical differences are shown between cultures grown under in vitro conditions and the organ from which they were derived. These differences are found among amino acids, organic acids, nucleic acids, and sugars. The potential use of the tissue culture approach for the study of the biosynthesis of ‘secondary compounds’ such as alkaloids and steroids is discussed.
Studies on the fermentative production of L‐isoleucine
Authors: Chibata Ichiro , Kisumi Masahiko , Ashikaga Yoshitaro
Published: May 2005

Several strains of Pseudomonas were selected by the screening test for organisms which are capable of producing L‐isoleucine.

With these selected bacteria, various cultural conditions suitable for the production and accumulation of L‐isoleucine were investigated. As a result, 12–14 mg/ml of L‐isoleucine was formed by shake culture in a medium containing α‐aminobutyric acid, glucose, cornsteep liquor, urea and inorganic salts.
Mathematical models for the product accumulation in microbiolgical processes
Authors: Shu Ping
Published: May 2005

A production model consisting of one or more exponential decay functions is proposed to represent the rate of accumulation of a product per unit weight of cell. This, together with a cell age distribution function, is used to describe the product accumulation in a fermentation process.

This postulate offers a unified concept applicable to both batch and continuous processes as well as problems arising from environmental changes. The idea is compatible with the current understanding of microbial physiology. It offers an interpretation for the controversy over cell‐product ratios observed in some batch and continuous fermentations when treated as conventional chemical reaction. The proposed postulate fits reasonably well with the lysine and lactic acid processes.
Miso—I. Preparation of soybeans for fermentation
Authors: Shibasaki K. , Hesseltine C. W.
Published: May 2005

The preparation of soybeans for fermentation is a very important part of the process for making miso, a traditional Japanese food. In general, soybeans from the United States are smaller and more pigmented than Japanese soybeans. Twenty‐eight American varieties, four Japanese varieties and one Chinese variety have been studied with respect to absorption of water and cooking. A variety of soaking and cooking conditions have been investigated. Some U.S. varieties absorb water and cook unevenly. Unevenness in cooking is not associated with the size of the beans within a variety.
Dihydroxyacetone: Production and uses
Authors: Green S. R. , Whalen E. A. , Molokie E.
Published: May 2005

Based on numerous reports in the literature, it appeared that the commerical production of dihydroxyacetone by microbial fermentation was not feasible due to the comparatively long duration of fermentation and the low total yield that could be obtained per fermentor. A new study has indicated that by adjusting environmental conditions and by modifying mash ingredients, commerical production of dihyroxyacetone via microbial oxidation of glycerol is practicable. The effect of these variables on the rate and extent of dihydroxyacetone production is discussed. The commerical and pharmaceutical uses of dihydroxyacetone and its derivatives is presented.
Purification and characterization of a Mr ∼66,000 lung‐derived (paracrine) growth factor that preferentially stimulates the in vitro proliferation of lung‐metastasizing tumor cells
Authors: Cavanaugh Philip G. , Nicolson Garth L.
Published: May 2005

In medium containing low concentrations of serum, rat 13762NF mammary adeno‐carcinoma cell lines and clones (MTPa and MTC; isolated from the locally growing tumor) of low metastatic potential to lung did not exhibit a growth response to lung‐conditioned medium, whereas a highly metastatic cell clone isolated from a spontaneous lung metastasis (MTLn3) did. The major growth‐promoting factor for MTLn3 cells from porcine and rat lung‐conditioned media was isolated by using a five‐step procedure (anion exchange chromatography, Affi‐gel blue affinity chroma‐tography, chromatofocusing, size exclusion chromatography, and preparative native gel electrophoresis). The lung‐derived factor that stimulated the growth of highly metastatic MTLn3 cells was a glycoprotein of Mr ≈66,000 (non‐reduced) or Mr ∼72,000 (reduced) and possessed a pI of 6.9–7.0. It preferentially promoted the growth of lung‐metastasizing tumor lines over their poorly lung‐metastasizing counterparts in three tumor systems: rat 13762NF mammary adenocarcinoma, murine B16 melanoma, and murine RAW 117 large‐cell lymphoma. The factor's growth‐stimulatory affect was inactivated by reduction or exposure to high temperature (95°C). Although the growth factor appears to be glycosylated, its molecular weight was not altered by treatment with the protein‐deglycosylating agent, trifluo‐romethane sulfonic acid. Cleavage of the protein by cyanogen bromide resulted in the formation of five fragments. Malignant cell response to this lung‐derived paracrine growth factor may be important in the successful formation of lung metastases.
Lung carcinoid cell lines have Bombesin‐like peptides and EGF receptors
Authors: Moody T. W. , Lee M. , Kris R. M. , Bellot F. , Bepler G. , Oie H. , Gazdar A. F.
Published: May 2005

The biochemical properties of lung cancer cell lines were investigated. Bombesin‐like peptides were present in three small cell lung cancer (SCLC) cell lines examined and three of four lung carcinoids but not in five non‐small cell lung cancer (NSCLC) cell lines. Therefore SCLC and some lung carcinoids, but not NSCLC, are enriched in neuroendocrine properties. In contrast, 125I‐EGF bound with high affinity to all five NSCLC cell lines and three of four lung carcinoids but not to the three SCLC cell lines examined. For lung carcinoid cell line NCI‐H727, 125I‐EGF bound with high affinity (Kd = 6 nM) to a single class of sites (Bmax = 110,000/cell). The 125I‐EGF bound was rapidly internalized at 37°C but not 4°C. Using Western blot techniques and antiphosphotyrosine antibodies, EGF induced phosphorylation of a major 170 Kd protein. Using immunoprecipitation techniques and anti‐EGF recep‐tor antibodies a major 170 Kd protein was labeled. These data indicate that biologically active EGF receptors are present on NSCLC and lung carcinoid cell lines.
Mycoplasma contamination alters 2′‐deoxyadenosine metabolism in deoxycoformycin‐treated mouse leukemia cells
Authors: Plagemann Peter G. W. , Woffendin Clive
Published: May 2005

Deoxycoformycin‐treated P388 and L1210 mouse leukemia cells salvage 2′‐deoxyadenosine from the medium only inefficiently, because deoxyadenosine deamination is blocked and its phosphorylation is limited by feedback controls. Mycoplasma contamination at a level that had no significant effect on the growth of the cells increased the salvage of deoxyadenosine >10 fold over a 90 min period of incubation at 37°C, but in this case deoxyadenosine was mainly incorporated into ribonucleotides and RNA via adenine formed from deoxyadenosine by mycoplasma adenosine phosphorylase. Deoxyadenosine was an efficient substrate for this enzyme, in contrast to 2′, 3′‐dideoxyadenosine which was not phosphorolyzed. Mycoplasma infection was confirmed by the presence of uracil phosphoribosyltransferase activity and by culture isolation. The contaminant has been identified as Mycoplasma orale. Mycoplasma infection had no effect on the deamination and phosphorylation of deoxyadenosine and adenosine, on the salvage of hypoxanthine and adenine, or on the degradation of dAMP and dATP by the cells or on their acid and alkaline phosphatase activities.
Plasminogen carbohydrate side chains in receptor binding and enzyme activation: A study of C6 glioma cells and primary cultures of rat hepatocytes
Authors: Hall Scott W. , Vandenberg Scott R. , Gonias Steven L.
Published: May 2005

The human [Glu1]‐plasminogen carbohydrate isozymes, plasminogen type I (Pg 1) and plasminogen type II (Pg 2), were separated by chromatography and studied in cell binding experiments at 4°C with primary cultures of rat hepatocytes and rat C6 glioma cells. In both cell systems, Pg 1 and Pg 2 bound to an equivalent number of receptors, apparently representing the same population of surface molecules The affinity for Pg 2 was slightly higher. With hepatocytes, the KD for Pg 1 was 3.2 ± 0.2 μM, and the KD for Pg 2 was 1.9 ± 0.1 μM, as determined from Scatchard transformations of the binding isotherms. The Bmax was approximately the same for both isozymes. With C6 cells, the KD for Pg 1 was 2.2 ± 0.1 μM vs. 1.5 ± 0.2 μM for Pg 2. Again, the Bmax was similar with both isozymes. 125I‐Pg 1 and 125I ‐Pg 2 were displaced from specific binding sites by either nonradiolabeled isozyme. The KI for Pg 2 was slightly lower than the KI for Pg 1 with hepatocytes (0.9 vs. 1.3 μM) and with C6 cells (0.6 vs. 1.1 μM). No displacement was detected with miniplasminogen at concentrations up to 5.0 μM. Activation of Pg 1 and Pg 2 by recombinant two‐chain tissue‐plasminogen activator (rt‐PA) was enhanced by hepatocyte cultures. The enhancing effect was greater with Pg 2. Hepatocyte cultures did not affect the activation of miniplasminogen by rt‐PA or the activation of plasminogen by streptokinase. Unlike the hepatocytes, C6 cells did not enhance the activation of plasminogen by rt‐PA or streptokinase; however, plasmin generated in the presence of C6 cells reacted less readily with α2 ‐antiplasmin.
Enzyme‐linked immunosorbent assay for the epidermal growth factor receptor
Authors: Stoscheck Christa M.
Published: May 2005

An enzyme‐linked immunosorbent assay (ELISA) for the epidermal growth factor (EGF) receptor was developed using three different antibody preparations, one of which is commercially available. Using one of the antisera (986), the assay could detect as few as 200 × 106 receptors. This is equal to 0.332 fmol. This sensitivity means that a minimum of 100 A‐431 cells (human carcinoma) or 5,000 normal cells are needed to quantitate the number of EGF receptors. Two of the antisera (986 and 451) recognized EGF receptors from placental tissue. EGF receptors from as little as 667 ng of placental membrane protein were detectable. The assay is highly species specific, with the sensitivity for the EGF receptor from different species dependent on the antiserum used. The commercial antibody, 29.1, had especially strong reactivity against pig and dog EGF receptors. An ELISA using this antibody had the capacity to detect the number of EGF receptors in 10 μg of liver membrane protein. The assay is sensitive to receptor conformation. The binding of antisera 986 and 451 to 1% sodium dodecyl sulfate (SDS)‐denatured receptor was reduced. The binding of antibody 29.1 was impaired by the presence of 1% Triton X‐100 but not the same levels of Tween‐20 or SDS. In addition to being a sensitive technique for the quantitation of the EGF receptor, this assay is very rapid, taking a total of 4 h. The microtiter dish format also allows hundreds of samples to be assayed at once. By using the appropriate antiserum and standards, the EGF receptor can be quantitated in tissues from humans, dogs, pigs, and mice.
Human uncoupling protein gene: Structure, comparison with rat gene, and assignment to the long arm of chromosome 4
Authors: Cassard Anne‐Marie , Bouillaud Frédéric , Mattei Marie‐Geneviève , Hentz Eliane , Raimbault Serge , Thomas Muriel , Ricquier Daniel
Published: May 2005

The uncoupling protein (UCP) gene encodes a unique mammalian mitochondrial proton carrier that induces heat production in brown adipocytes. Human UCP gene was isolated and its organization analyzed. A comparison was made with rat UCP gene. Human UCP gene spans 13 Kb and contains a transcribed region that covers 9 Kb of the human genome. All of the exons were also sequenced except the extreme end of the 3′ untranslated region. Two Kb DNA upstream the TATA box were also sequenced. This region contains several fragments that are highly homologous to the gene of rat UCP. Neither CCAAT sequence nor Sp I binding motif were detected. Human UCP gene is split into six exons. The complete amino acid sequence of the protein was determined. Human UCP has 305 amino acids and a molecular weight of 32,786. It has no N‐terminal targeting sequence. It is 79% homologous to rat UCP both at nucleotidic and amino acid levels. The primary structure of UCP is significantly homologous to the primary structure of the human T1 ADP/ATP carrier, particularly in the C‐terminal extremity, which is supposed to contain a nucleotide‐ binding site in both proteins. Human UCP gene is single type, as it is in rodents. Two genomic fragments were used to detect a 1.9 Kb mRNA in human perirenal brown adipose tissue. Using in situ hybridization, UCP gene was assigned in humans to chromosome 4 in q31. Interestingly, the Tl gene encoding the heart‐skeletal muscle ADP/ATP carrier has recently been shown to be on the same chromosome (Li et al. Biol Chem 264:13998, 1989).
Proteoglycan synthesis by normal and neoplastic human transitional epithelial cells
Authors: Knudson Warren , Subbaiah Subbalakshmi , Pauli Bendicht U.
Published: May 2005

Metabolically 35S‐labeled proteoglycans were isolated from cell‐associated matrices and media of confluent cultures of human normal transitional epithelial cells and HCV‐29T transitional carcinoma cells. On Sepharose CL‐4B columns, the cell‐associated proteoglycans synthesized from both cell types separated into three identical size classes, termed Cl, Cll, and Clll. Normal epithelial cell C‐fractions eluted in a 22:34:45 proportion and contained 64%, 64%, and 72% heparan sulfate, whereas corresponding HCV‐29T fractions eluted in a 29:11:60 proportion, and contained 91%, 77%, and 70% heparan sulfate, respectively. Medium proteoglycans from normal cells separated into two size classes in a proportion of 6:94 and were composed of 35% and 50% heparan sulfate. HCV‐29T medium contained only one size class of proteoglycans consisting of 23% heparan sulfate. The remaining percent‐ages were accounted for by chondroitin/dermatan sulfate. On isopycnic CsCI gradients, proteoglycan fractions from normal cells had buoyant densities that were higher than the corresponding fractions from HCV‐29T cells. DEAE‐Sephacel chromatography showed that cell and medium associated heparan sulfate from HCV‐29T cells was consistently of lower charge density (undersulfated) than that from normal epithelial cells. In contrast, the chondroitin/dermatan sulfate of HCV‐29T was of a charge density similar to that of normal cells. These as well as other structural and compositional differences in the proteoglycan may account, at least in part, for the altered behavioral traits of highly invasive carcinoma cells.
Coexpression of tumor‐associated α2‐macroglobulin and growth factors in human melanoma cell lines
Authors: Lizonová Alena , Bízik Jozef , Grófóva Marta , Vaheri Antti
Published: May 2005

α2‐Macroglobulin (α2M) is known as an inhibitor of various proteinases and to bind several of the growth factors. We previously demonstrated that clonal variation existsin the production of α2M in a human melanoma and that this variation may be associated with growth stimulation. We have now analyzed six human melanoma cell lines for the simultaneous expression of TGF‐α TGF‐β, PDGF‐A chain, PDGF‐B chain, and tumor‐associated α2M. In Northern blot analysis TGF‐α was detected in four of the cell lines, TGF‐β in all, PDGF‐A chain in three, and PDGF‐B chain in none of the cell lines. α2M, detected by immunoblotting, varied significantly between the different melanoma cell lines and only one cell line was found to be negative. Evaluation of growth‐promoting activity in conditioned media suggested that α2‐macroglobulin, secreted by these tumor cell lines, is a significant modulator of melanoma cell growth.
Structural and functional analysis of the rat testis‐specific histone H1t gene
Authors: Grimes Sidney R. , Wolfe Steven A. , Anderson Jeffrey V. , Stein Gary S. , Stein Janet L.
Published: May 2005

A 6.86 kb rat genomic DNA fragment containing the testis‐specific histone H1t gene and the histone H4t gene has been sequenced. S1‐nuclease protection analyses of total cellular RNA from rat liver and testis showed that histone H1t mRNA was present only in testis. Examination of various highly enriched populations of rat testis cell types revealed that H1t mRNA was found exclusively in a fraction enriched in pachytene spermatocytes. When protein, DNA interactions within the proximal promoter region of the histone H1t gene were examined by electrophoretic mobility shift assays, only minor differences were found in mobility shift patterns of the H1t promoter in assays comparing binding of nuclear proteins from pachytene spermatocytes and early spermatids. However, major differences in binding were observed upon comparing nuclear proteins from rat pachytene spermatocytes to liver. Comparison of binding patterns of rat testis, rat hepatoma H4 cells, HeLa cells, and COS‐1 cells also revealed dramatic differences. Transcriptional activity of the histone H1t promoter was examined by measuring H1t promoted chloramphenicol acetyltransferase (CAT) mRNA levels in transient experession assays in transfected rat hepatoma H4 cells, HeLa cells, and COS‐1 cells. These assays revealed that the histone H1t promoted CAT gene functioned poorly in HeLa cells and COS‐1 cells compared to expression with the parent SV40 promoted vector pSV2CAT. The H1t promoted CAT gene apparently did not work at all in transfected rat hepatoma H4 cells, which is consistent with testis germinal cell specific expression of the histone H1t gene.
mRNA transcription determines the lag period for the induction of pineal melatonin synthesis in the Syrian hamster pineal gland
Authors: Gonzalez‐Brito Aldo , Troiani Maureen E. , Menendez‐Pelaez Armando , Delgado Maria J. , Reiter Russel J.
Published: May 2005

The nocturnal pattern of Syrian hamster pineal melatonin synthesis is characterized by a 6–8 h lag period, followed by a late‐night, short‐duration peak in both N‐acetyltransferase (NAT) activity and melatonin content. Administration of cycloheximide (20 mg/kg body weight) given either at the time of lights out or 4 h into the dark phase to Syrian hamsters blocked the nocturnal increase in both pineal NAT activity and melatonin content. Actinomycin D (5 mg/kg body weight) prevented the nocturnal increase in both constituents only when it was administered at darkness onset, being significantly less effective when injected after 4 h of dark exposure. Reinduction of melatonin production by isoproterenol (2 mg/kg body weight) administration to acutely light‐exposed animals during late darkness was prevented by cycloheximide, but not by actinomycin D administration. The results suggest that whereas Syrian hamster pineal melatonin production requires protein synthesis both early and late in the dark phase, the transcription of a putative NAT‐related mRNA, which occurs only during the early night, seems to determine the lag period in melatonin synthesis and pineal responsiveness to β‐adrenergic receptor agonist stimulation.
Detection and localization of actin mRNA isoforms in chicken muscle cells by in situ hybridization using biotinated oligonucleotide probes
Authors: Taneja Krishan L. , Singer Robert H.
Published: May 2005

We have developed in situ hybridization methodology for nonisotopically labeled oligonucleotide probes to detect cellular mRNA with improved speed, convenience, and resolution over previous techniques. Previous work using isotopically labeled oligonucleotide probes characterized important parameters for in situ hybridization (Anal Biochem 166:389, 1987). Eleven oligonucleotide probes were made to coding and noncoding regions of chick β‐actin mRNA and one oligonucleotide probe to chick α‐cardiac actin mRNA. All the probes were 3′ end‐labeled with bio‐11‐dUTP using terminal transferase, and the labeled probes were hybridized to chicken myoblast and myotube cultures. The hybridized probe was detected using a streptavidin‐alkaline phosphatase conjugate. Our assay for the success of probe hybridization and detection was the demonstration of β‐actin mRNA highly localized in the lamellipodia of single cells (Lawrence and Singer, Cell 45:407, 1986) as well as the expression of α‐cardiac actin mRNA and the repression of β‐actin mRNA in differentiating myoblasts and in myotubes. With the α‐cardiac probe, we found that this mRNA was distributed all over the cytoplasm of myotubes and differentiated (bipolar) single cells and negative in undifferentiated single cells and at the ends of myotubes. When β‐actin probes were used, two of 11 probes were highly sensitive, and, in pooling them together, the localization of β‐actin mRNA in fibroblastic single cells was evident at the leading edge of the motile cells, the lamellipodium. β‐Actin mRNA was not detected in myotubes except at the ends where contact was made with substrate. This indicates that both β and cardiac actin mRNA can coexist in the same myotube cytoplasm but at different locations.
Phenotype suppression: A postulated molecular mechanism for mediating the relationship of proliferation and differentiation by Fos/Jun interactions at AP‐1 sites in steroid responsive promoter elements of tissue‐specific genes
Authors: Lian Jane B. , Stein Gary S. , Bortell Rita , Owen Thomas A.
Published: May 2005

There is a generalized reciprocal relationship between cell growth and expression of genes that occurs following completion of proliferation, which supports the progressive development of cell and tissue phenotypes. Molecular mechanisms which couple the shutdown of proliferation with initiation of tissue‐specific gene transcription have been addressed experimentally in cultures of primary diploid osteoblasts that undergo a growth and differentiation developmental sequence. Evidence is presented for a model which postulates that genes transcribed post‐proliferatively are suppressed during cell growth by binding of the Fos/Jun protein complex to AP‐1 Promoter sites associated with vitamin D responsive elements of several genes encoding osteoblast phenotype markers (Type I collagen, alkaline phosphatase, osteocalcin).
Zinc finger motif for single‐stranded nucleic acids? investigations by nuclear magnetic resonance
Authors: Summers Michael F.
Published: May 2005

Nuclear magnetic resonance (NMR) methods have been used to address issues regarding the relevance and feasibility of zinc binding to “zinc finger‐like” sequences of the type C‐X2‐C‐X4‐H‐X4‐C [referred to as CCHC or retroviral‐type (RT) zinc finger sequences]. One‐dimensional (1D) NMR experiments with an 18‐residue synthetic peptide containing the amino acid sequence of an HIV‐1 RT‐zinc finger domain (HIV1‐F1) indicate that the sequences are capable of binding zinc tightly and stoichiometrically. 1H‐113Cd spin echo difference NMR data confirm that the Cys and His amino acids are coordinated to metal in the 113Cd adduct. The 3D structure of the zinc adduct [Zn(HIV1‐F1)] was determined to high atomic resolution by a new NMR‐based approach that utilizes 2D‐NOESY back‐calculations as a measure of the consistency between the structures and the experimental data. Several interesting structural features were observed, including (1) the presence of extensive internal hydrogen bonding, and (2) the similarity of the folding of the first six residues to the folding observed by X‐ray crystallography for related residues in the iron domain of rubredoxin. Structural constraints associated with conservatively substituted glycines provide further rationale for the physiological relevance of the zinc adduct. Similar NMR and structural results have been obtained for the second HIV‐1 RT‐zinc finger peptide, Zn(HIV1‐F2). NMR studies of the zinc adduct with the NCP isolated directly from HIV‐1 particles provide solid evidence that zinc finger domains are formed that are conformationally similar (if not identical) to the peptide structures. The motif has been found in several other single‐stranded nucleic acid binding proteins, including a human protein, and may represent a common motif analogous to the “classical” zinc finger motif widely distributed in duplex‐DNA binding proteins.