bluuebunny/crossref_metadata_2025 huggingface dataset:
The effect of elevated temperature on flame‐retardant treated wools and other fibers
Authors: Gordon P. G. , Logan R. I.
Published: December 2004

The limiting oxygen indices of flame‐retardant treated wools have been determined at environmental temperatures up to 380°C. As the ambient temperature increases, the LOI decreases significantly until, within the temperature range of 308°C and 325°C, it reaches a minimum value, Above 325°C, the LOI of the carbonaceous residue increases rapidly with temperature. The minimum value reached for a number of retardant treated wools was below that for untreated wool. Broadly similar behaviour is exhibited by flame‐retardant cotton, modacrylic and Nomex°, although with the latter there is no increase in oxygen index at the upper end of the temperature range studied.
Structure and radiation properties of large‐scale natural gas/air diffusion flames
Authors: Gore J. P. , Faeth G. M. , Evans D. , Pfenning D. B.
Published: December 2004

Recent data from large‐scale turbulent natural gas/air diffusion flames (135‐210 MW) were used to evaluate analysis of flame structure and radiation properties. The conserved‐scalar formalism, in conjunction with the laminar flamelet concept, was used to predict radiative heat fluxes. The narrow‐band model considered the nonluminous gas bands of water vapor, carbon dioxide, methane and carbon monoxide in the 1000‐6000mm wavelength range. Structure predictions were encouraging, with discrepancies for mean temperatures (ca200 K in the hottest portions of the flames) comparable to experimental uncertainties, due to thermocouple errors, flame disturbances from ambient winds and lifting and external expansion effects near the injector. Radiative heat flux predictions were also reasonably good, e.g. predictions based on mean scalar properties were generally 15% lower than the measurements. The findings also suggest that continuum radiation from soot is negligible for these flames.
The conflagration of two large department stores in the centre of athens
Authors: Papaioannou Kyriakos
Published: December 2004

A conflagration of two large department stores which occurred simultaneously one night in the centre of Athens is described and the construction of buildings involved in the fire, the scenario and the fire damage assessment are given. The behaviour of structural elements during and after the fire has been studied and the causes and the mechanism of collapse of a large part of a multi‐storey concrete building analyzed.
Ignitability measurements with the cone calorimeter
Authors: Babrauskas Vytenis , Parker William J.
Published: December 2004

The Cone Calorimeter is a new‐generation instrument developed primarily for making rate of heat release measurements. This instrument, containing a uniform and well‐characterized irradiance source, was also seen to be useful for making measurements of radiant ignition on materials. Data have now been collected for a wide range of illustrating the performance of similar materials in other apparatuses. Finally, for a selected material, Douglas fir particle board, a detailed comparison with an ignition model has been made.
A literature review of the chemical nature and toxicity of the decomposition products of polyethylenes
Authors: Paabo Maya , Levin Barbara C.
Published: December 2004

The literature on polyethylenes has been reviewed with an emphasis on the identification of gaseous products generated under various thermal decomposition conditions and the toxicity of those products. This review is limited to publications in English through 1984. The analytical chemical studies of the thermal decomposition products generated under vacuum, inert and oxidative experimental conditions are described. In oxidative atmosphere, which most closely simulate real fire conditions, carbon monoxide (CO) was found to be the predominant toxicant. Acrolein was another toxicant often noted in these reviewed studies. More acrolein was generated under non‐flaming than under flaming conditions. Results from seven different test procedures were considered in assessing the acute inhalation toxicity of combustion products from various polyethylene formulations. The combustion products generated from the polyethylenes studied in the non‐flaming mode appeared to be slightly more toxic than those produced in the flaming mode. In the non‐flaming mode the LC50 values ranged from 5 to 75 mg l−1. In the flaming mode the LC50 values ranged from 31 to 51 mg l−1. The toxicity of the degradation products of polyethylenes appears to be similar to that found for other common materials designed for the same end uses.
On the equivalent fire exposure
Authors: Harmathy T. Z.
Published: December 2004

The equivalent fire exposure (EFE) is visualized as a quantifier of the destructive potential of real‐world compartment fires in terms of the time to failure of building elements in standard test fires. Five methods of calculating the EFE are reviewed and compared in the light of some experimental data.
Evolution of toxic gases from burning polymeric materials in a small‐scale box model
Authors: Morikawa Tokio
Published: December 2004

Various polymeric materials were combusted in a small‐scale box model equipped with an air supply system to determine the evolution of toxic gases and evaluate the toxicity of the environment containing these gases. There were cases where concentrations of HCN, acrolein and formaldehyde were higher in terms of potential toxicity than that of CO. Overall experimental results indicate that small‐scale experiments are useful in evaluating combustion toxicity of materials.
Fibre mortar composites in fire conditions
Authors: Sarvaranta Leena , Mikkola Esko
Published: December 2004

A small‐scale test series was carried out using the heating system (radiant exposure) of a cone calorimeter to detect any differences in the way different fibres affect the thermal properties of a standard mortar. The fibres were different polypropylene, polyacrylonitrile, aramide, carbon or steel. Fibres affect the release of moisture from the fibre mortar material. Local pressures caused by water vaporization due to rapid heating can be decreased by incorporating fibres. Fibres have a weak insulating effect. However, use of polyacrylonitrile fibres in mortar may increase the risk to spalling under rapid thermal exposure such as fire. The moisture level in specimens is highly significant for their thermal properties and hence their fire behavior.
Bench‐scale evaluations and mechanistic studies of intumescent/fire‐protective coatings for polyvinyl chloride nitrile rubber
Authors: Pande Seetar G. , Adkins James , Williams Frederick W. , Tatem Patricia A.
Published: December 2004

The object of this study was to identify, for future large‐scale testing, and adequate fire‐protective coating for the substrate, polyvinyl chloride (PVC) nitrile rubber (MIL‐P‐15280 Rev H). Fifteen fire protective coatings which included ten intumescent, two ablatives, two fire retardants and one photon diffusive coatings were evaluated using bench‐scale thermal insults. To discern the possible mechanism(s) whereby the coatings offer fire protection, the effect of radiant heat versus the flame source employed was investigated and thermogravimetric analysis (TGA) of the neat coatings was performed. In selected cases, the effect of coating thickness and repeatability of the results were evaluated. The differences in coating effectiveness, and the varied repeatability in three of the four cases examined, focus on the inherent complexity of intumescence, as well as on the importance of scaled‐up testing of coatings that appeared promising. Thermogravimetric analyses of the coatings indicate that two selected TGA measurements/parameters, when used in conjunction, appear useful in characterizing mechanistic differences between the less effective and more effective coatings. Based on the rigorous criterion adopted, one candidate (a water‐based intumescent coating at 100 mil (2.54 mm) thickness) appears promising for the substrate, PVC nitrile rubber. Its effectiveness is attributable to it exhibiting good insulative and re‐radiative properties and an apparent low susceptibility to crack formation.
Evaluation of laboratory gallery fire tests of conveyor belting
Authors: Mintz K. J.
Published: December 2004

Two mid‐scale laboratory gallery fire tests, the propane gallery and the BELT test, were constructed and evaluated. In both cases the fundamental parameter that can be used for ranking flammability of a belting is the total quantity of heat input into the sample, rather than length burned or flame‐out time. The temperature and velocity of the ventilating air used were found, experimentally and theoretically, to be critical factors in determining the results of the tests. The two tests correlated qualitatively on a pass|fail basis; however, the BELT test was affected more by the thickness of the sample: the thicker, the more probable to pass the test. The BELT test has the advantages of easier control and producing fewer pollutants. The results of BELT, propane gallery and critical oxygen index tests on some beltings are compared.
Concepts for fire protection of passenger rail transportation vehicles: Past, present, and future
Authors: Peacock Richard D. , Reneke Paul A. , Jones Walter W. , Bukowski Richard W. , Babrauskas Vytenis
Published: December 2004

Recent advances in passenger rail transportation, fire test methods, and hazard analysis necessitate re‐examination of requirements for fire safety. Several studies have indicated nearly random ability of current bench‐scale tests to predicts actual fire behavior. Fire safety in any application, including transportation, requires a multi‐faceted approach. The effects of vehicle design, material selection, detection and suppression systems, and emergency egress and their interaction, on the overall fire safety of the passenger trains must all be considered. The strengths and weakness of current methods for measuring the fire performance of rail transportation systems are evaluated. A systems approach to fire safety which address typical passenger train fire scenatios is analyzed. A rationale is presented for the direction in which most fire science‐oriented organizations in the world are clearly headed – the use of fire hazard and fire risk assessment methods supported by measurement methods based on heat release rate.
An investigation into the effects of gravity level on rate of heat release and time to ignition
Authors: Bryant D.
Published: December 2004

Two experiments were performed on board an aircraft flying repeated parabolic trajectories to generate free‐fal conditions. The first experiment investigates the way in which rate of heat release (RHR) varies with gravity for a candle flame under an imposed low‐speed flow. In line with previous studies of flame spread rate it has been shown that rate of heat release drops significantly in imcrogravity. The heat loss due to radiation decreases by a larger proportion than that due to non‐radiative processes indicating a lower flame temperature. The RHR from a microgravity flame is flow rate dependent, increasing for increased flow rate at air speeds under 0.03 ms−1. For the geometry used in this experiment hypergravity caused only a small increase in RHR. The second experiment studied the ignitability of thermoplastics under an imposed radiant heat flux. The ignition test apparatus consists of a conical spiral heating element positioned horizontally above the sample, a continuous spark ignition source and a removable heat shield. Experiments were conducted in a sealed pressure chamber on samples of either PMMA or POM, 1.5 mm thick, with a ceramic backing. There is some indication that gravity influences the time to ignition for some materials.
Measurements of the severity of fires involving private motor vehicles
Authors: Shipp Martin , Spearpoint Michael
Published: December 2004

This paper presents the results of full‐scale fires in two private motor vehicles conducted under insturmented calorimeter hoods for the Channel Tunnel Safety Unit, Department of Transport. Measurements of heat release rate, temperatures and other parameters of fire severity are given. The results were used for the assessment of the specification and design of the shuttle wagons and in the subsequent computer modelling calculations to analyse the impact of such a fire within a shuttle wagon. The fires were well ventilated and allowed to develop fully before firefighting intervention. Of the two tests the first burned for 17 min with the gas temperature in the rig reaching 1250°C and with a peak total heat output of at least 7½ MW before being extinguished. The other burned for 57 min, with gas temperatures reaching 1125°C and a pead heat output of 4½ MW.
Core substructure in cyanobacterial phycobilisomes
Authors: Gingrich Jeffrey C. , Lundell Daniel J. , Glazer Alexander N.
Published: December 2004

The tricylindrical core of Synechocystis 6701 phycobilisomes is made up of four types of allophycocyanin‐containing complexes: A, (αAP βAP)3; B, (αAP βAP)3 .10K; C, (ααβ).10K; D, (αAP βAP)2.18.5K.99K; where AP is allophycocyanin, APB is allophycocyanin B, and 10K, 18.5K, and 99K are polypeptides of 10,000, 18,500, and 99,000 daltons, respectively. The 18.5K polypeptide is a hitherto unrecognized biliprotein subunit with a single phycocyanobilin prosthetic group. The tricylindrical core is made up of 12 subcomplexes in the molar ratio of A:B:C:D: of 4:4:2:2. Complexes C and D act as terminal energy acceptors. From these results and previous analysis of the bicylindrical core of Synechococcus 6301 phycobilisomes [14,15] it is proposed that the two cylinders of the Synechocystis 6701 core, proximal to the thylakoid membrane, each have the composition ABCD, and that the distal cylinder has the composition A2B2.
Transport of hemolysin by Escherichia coli
Authors: Härtlein Michael , Schießl Sigrid , Wagner Wilma , Rdest Ursula , Kreft Jürgen , Goebel Werner
Published: December 2004

The hemolytic phenotype in Escherichia coli is determined by four genes. Two (hlyC and hlyA) determine the synthesis of a hemolytically active protein which is transported across the cytoplasmic membrane. The other two genes (hlyBa and hlyBb) encode two proteins which are located in the outer membrane and seem to form a specific transport system for hemolysin across the outer membrane. The primary product of gene hlyA is a protein (protein A) of 106,000 daltons which is nonhemolytic and which is not transported. No signal peptide can be recognized at its N‐terminus. In the presence of the hlyC gene product (protein C), the 106,000‐dalton protein is processed to the major proteolytic product of 58,000 daltons, which is hemolytically active and is transported across the cytoplasmic membrane. Several other proteolytic fragments of the 106,000‐dalton protein are also generated. During the transport of the 58,000‐dalton fragment (and possible other proteolytic fragments of hlyA gene product), the C protein remains in the cytoplasm. In the absence of hlyBa and hlyBb the entire hemolytic activity (mainly associated with the 58,000‐dalton protein) is located in the periplasm: Studies on the location of hcmolysin in hlyBa and hlyBb mutants suggest that the gene product of hlyBa (protein Ba) binds hemolysin and leads it through the outer membrane whereas the gene product of hlyBb (protein Bb) releases hemolysin from the outer membrane. This transport system is specific for E coli hemoiysin. Other periplasmic enzymes of E coli and heterologous hemolysin (cereolysin) are not transported.
Prolactin receptor expression in monolayer cultures of rabbit mammary epithelial cells: Pre‐ and postpartum [125I]‐prolactin binding activity
Authors: Soltysiak R. M. , Fellows R. E.
Published: December 2004

Expression of specific [125I]‐prolactin‐binding sites under culture conditions has been investigated for isolated mammary epithelial cells from virgin, pregnant, and lactating rabbits. Primary monolayer cultures were obtained by sequential enzymatic dispersion of mammary tissue followed by 48 hr incubation in a medium selective for epithelial cells. Scatchard analyses of binding data obtained from these cultures indicated a single class of receptor sites, the affinity constant of which (2.5 × 109 M−1) did not vary significantly during mammary development. The number of prolactin receptors, however, expressed by virgin and early pregnant epithelial cells was significantly increased over those from late pregnancy or lactation. Less differentiated cells also respond to growth in pregnant rabbit serum with an increase in specific [125I]‐prolactin binding. The diminished receptor expression by cells obtained after 17 days of pregnancy coincides with the attainment of secretory capacity in the animal, and may reflect the influence of the low serum prolactin or high progesterone levels circulating during the last trimester in the rabbit, or be the cultural expression of secretory differentiation.
Reconstitution of the low density lipoprotein receptor
Authors: Schneider Wolfgang J.
Published: December 2004

The receptor for low density lipoprotein was purified from bovine adrenal cortex in the presence of the nonionic detergent octylglucoside. Receptors were incorporated into the bilayer of egg phosphatidylcholine vesicles by a detergent‐dialysis method. Reconstituted receptors were functional in that they bound low density lipoprotein as well as a monoclonal antibody directed against the receptor in a specific, saturable fashion. Binding activity of reconstituted receptors was measured by a gel chromatography assay. The orientation of the receptor molecule within the phospholipid bilayer was investigated by binding assays following proteolytic digestion. Reconstituted receptors showed an orientation that was functionally indistinguishable from that of low density lipoprotein receptors in the plasma membrane of intact human fibroblasts.
Isolation of PS II reaction centre and its relationship to the minor chlorophyll‐protein complexes
Authors: Camm Edith L. , Green Beverley R.
Published: December 2004

Evidence is presented for the identification of the chlorophyll‐ protein complex CPa‐1 (CP 47) as the reaction centre of photosystem II (PS II). We have developed a simple, rapid method using octyl glucoside solubilization to obtain preparations from spinach and barley that are highly enriched in PS II reaction centre activity (measured as the light‐driven reduction of diphenylcarbazide by 2,6‐dichlorophen‐olindophenol). These preparations contain only the two minor chlorophyll‐protein complexes CPa‐1 and CPa‐2. During centrifugation on a sucrose density gradient, there is a partial separation of the two CPa complexes from each other, and a complete separation from other chlorophyll‐protein complexes. The PS II activity comigrates with CPa‐1 but not CPa‐2, strongly suggesting that the former is the reaction centre complex of PS II. Reaction centre preparations are sensitive to the herbicide 3(3,4‐dichlorophenyl)‐1,1‐dimethylurea (DCMU), but only at much higher concentrations than those required to inhibit intact thylakoid membranes.

A model of PS II incorporating our current knowledge of the chlorophyll‐protein complexes is presented. It is proposed that CPa‐2 and the chlorophyll a + b complex CP 29 may function as internal antenna complexes surrounding the reaction centre, with the addition of variable amounts of the major chlorophyll a+b light‐harvesting complex.
Effect of physiological concentrations of insulin and antidiabetic drugs on RNA release from isolated liver nuclei
Authors: Schumm Dorothy E. , Webb Thomas E.
Published: December 2004

The addition of 10−11M insulin to a cell‐free system from rat liver promotes the release of messengerlike RNA from isolated prelabeled nuclei. The stimulation was similar whether the nuclei were preincubatcd with insulin, or if insulin was added directly to the cell‐free system with or without a protease inhibitor. Dot blot hybridization using cloned cDNA for α2u‐globulin mRNA showed that this was one of the messages whose release was enhanced by insulin. Nuclei isolated from rats treated with either of the antidiabetics tolbutamide or tolazamide showed no increase in RNA release in the presence of insulin over the concentration range 10−5−10−14 M. Furthermore, these nuclei did not release detectable levels of α2u‐globulin mRNA.
Release and purification of trypanosoma brucei variant surface glycoprotein
Authors: Cross George A. M.
Published: December 2004

Conditions affecting the solubilization of variant surface glycoprotein (VSG) from Trypanosoma brucei have been investigated. The results obtained form the basis for a convenient and efficient method for VSG purification. VSG release from the cell surface was temperature‐dependent, following osmotic lysis at 0 °C, and was inhibited by low concentrations of Zn2+ but not by tosyl‐lysine chloromethyl‐ketone (TLCK), phenylmethylsulfonylfluoride (PMSF), or iodoacetamide. These and other results eliminated the possibility that release was due to proteolytic cleavage of the C‐terminal hydrophobic tail present on newly synthesized VSG. Bolton and Hunter reagent reacted with several components on living cells.
Synthesis, processing, and secretion of hepatic very low density lipoprotein
Authors: Janero David R. , Siuta‐Mangano Patricia , Miller Kurt W. , Lane M. Daniel
Published: December 2004

Very low density lipoprotein (VLDL) is the major vehicle in the plasma which carries triacylglycerol synthesized in the liver to peripheral tissues for utilization. Estrogen‐induced chick parenchymal liver cells (hepatocytes) synthesize and secrete large amounts of VLDL. These cells, in a primary monolayer culture system developed in this laboratory, have been employed to study the operative and regulatory aspects of VLDL synthesis, assembly, and secretion. Some 10 min are required for the translation of the principle VLDL protein constituent, apolipoprotein B, and 30–35 min are required for the two newly translated chick VLDL apolipoproteins, apolipoprotein B and apolipoprotein II, to be secreted. Apolipoprotein B is synthesized on membrane‐bound polysomes as a contiguous polypeptide chain of 350K molecular weight (MW) and is not assembled posttranslationally from smaller‐peptide precursors. Translocation of puromycin‐discharged apolipoprotein B nascent chains into the endoplasmic reticulum lumen and their subsequent secretion are independent of both ongoing protein synthesis and the attachment of the nascent peptides to ribosomes. Apolipoprotein B nascent chains discharged by puromycin assemble with glycerolipid (mainly triacylglycerol) and are secreted as immunoprecipitable VLDL. Core oligosaccharides are added to the apolipoprotein B nascent chain co‐translationally in at least two stages, at molecular weights of ∼ 120K and ∼ 280K. Inhibition of N‐linked glycosylation of apolipoprotein B with tunicamycin affects neither the assembly of glycerolipids into VLDL nor the secretion of the VLDL particle, indicating that aglyco‐apolipoprotein B can serve as a functional component for VLDL assembly and secretion. Active synthesis of the VLDL apolipoproteins is required, however, for glycerolipid assembly into VLDL and secretion from the hepatocyte. The differential kinetics with which newly synthesized apolipoproteins and glycerolipids are secreted as VLDL and the timing of the effects of protein‐synthesis inhibitors on their secretion indicate that VLDL constituents are assembled sequentially in the intact liver cell. The bulk of the VLDL triacylglycerol and some VLDL phosphoglyceride is introduced early in the secretory pathway proximal, yet subsequent to apopeptide synthesis, while a significant fraction of VLDL phosphoglyceride associates with the resulting triacylglycerol‐rich lipid‐protein complexes just prior to their secretion as mature VLDL. Within the context of current models for VLDL structure, the late assembly of phosphoglyceride into VLDL is taken to represent a surface maturation of the nascent VLDL particle.
The natural heterogeneity of trypanosoma cruzi: Biological and medical implications
Authors: Dvorak James A.
Published: December 2004

Trypanosoma cruzi is a heterogeneous group of parasites. The imposition of natural or artificial pressures can result in the selection of subsets of the population with concomitant changes in characteristics used to evaluate the group. In order to ascertain the extent of heterogeneity, stocks of single‐cell clones were prepared from various sources. Selected cell biological, biochemical, immunochemical, parasitological, and histopathological parameters of these clones have been studied. A ten‐fold difference in the rate of growth of the epimastigote stage of T cruzi clones has been observed. The extracellular growth rates of the clones correlate with the rate of growth of the obligate intracellular amastigote stage and consequently, the length of intracellular cycle of the parasite. A 40% difference in the amount of total DNA/parasite has been found between clones. Although the amount of DNA/kinetoplast and nucleus varies between clones, the major contribution to the differences in total DNA/parasite appears to be the nucleus. From 16 to 35 antigens have been demonstrated in the T cruzi clones assayed to date. Five to seven of these antigens are common to all of the stocks assayed. However, both isolate‐ and clone‐specific antigens have also been demonstrated. The susceptibility of inbred strains of mice to T cruzi clones varies with the clone of the parasite. These data imply that the genetics of the parasite as well as the host modulate both the course and outcome of a T cruzi infection. The influence of monosaccharides on the receptor‐mediated infection of vertebrate cells by trypomastigotes of T cruzi also varies between clones. The implications of these findings upon our concept and understanding of present and future problems in Chagas disease are discussed.
The in vitro trypanocidal activity of N‐substituted p‐benzoquinone imines: Assessment of biochemical structure‐activity relationships using the Hansch approach
Authors: Grady Robert W. , Blobstein Steven H. , Meshnick Steven R. , Ulrich Peter C. , Cerami Anthony , Amirmoazzami Jafargholi , Hodnett Ernest M.
Published: December 2004

It has previously been found that naphthoquinones can potentiate the rate of hydrogen peroxide production by mitochondrial preparations of Trypanosoma brucei brucei and that organisms treated with naphthoquinones are more susceptible to lysis, especially in the presence of compounds such as heme, which promote the homolytic cleavage of hydrogen peroxide. We have evaluated the lytic effect of various N‐substituted p‐benzoquinone imines both in vitro and in vivo and have attempted to correlate their structure with trypanocidal activity using the Hansch approach. While none of the compounds tested proved to be active in vivo, all caused the lysis of trypanosomes in vitro. The parameters that correlated best with trypanocidal activity were the conditional redox potential, the lipophilicity of the substituent attached to the nitrogen atom and the number of active hydrogens on the quinoncid ring. These findings suggest two possible modes of action, which may in fact be related. Conjugate nucleophilic addition and/or oxidative damage could be responsible for lysis of the parasites. These same compounds were previously found to be active against the ascitic sarcoma 180 in mice. The strong correlation between antineoplastic activity in vivo and trypanocidal activity in vitro suggests a similar mode of action in both cases. Further studies aimed at developing a quinonelike compound that will be active against trypanosomes in vivo are now in progress.
Phosphoproteins and the phosphoenolpyruvate: Sugar phosphotransferase system in salmonella typhimurium and escherichia coli: Evidence for IIIMannose, IIIFructose, IIIGlucitol, and the phosphorylation of enzyme IIMannitol and enzyme IIN‐acetylglucosamine
Authors: Waygood E. Bruce , Mattoo Roshan L. , Peri Krishna G.
Published: December 2004

Phosphoproteins produced by the incubation of crude extracts of Salmonella typhimurium and Escherichia coli with either [32P]phosphoenolpyruvate or [γ32P]ATP have been resolved and detected using sodium dodecyl sulphate poly‐acrylamide gel electrophoresis and autoradiography. Simple techniques were found such that distinctions could be made between phosphoproteins containing acid‐labile or stable phosphoamino acids and between N1‐P‐histidine and N3‐P‐histidine. Phosphoproteins were found to be primarily formed from phosphoenolpyruvate, but because of an efficient phosphoexchange, ATP also led to the formation of the major phosphoenolpyruvate‐dependent phosphoproteins. These proteins had the following apparent subunit molecular weights: 65,000, 65,000, 62,000, 48,000, 40,000, 33,000, 25,000, 20,000, 14,000, 13,000, 9,000, 8,000. Major ATP‐dependent phosphoproteins were detected with apparent subunit molecular weights of 75,000, 46,000, 30,000, and 15,000. Other minor phosphoproteins were detected. The phosphorylation of the 48,000‐ and 25,000‐MW proteins by phos‐phoenolpyruvate was independent of the phosphoenolpyruvate:sugar phospho‐transferase system (PTS). The PTS phosphoproteins were identified as enzyme I (soluble; MW = 65,000); enzyme IIN‐acetylglucosamine (membrane bound; MW = 65,000); enzyme IImannitol (membrane bound; MW = 62,000); IIIfructose (soluble; MW = 40,000); IIImannose (partially membrane associated; MW = 33,000); IIIglucose (soluble; MW = 20,000); IIIglucitol (soluble; MW = 13‐14,000); HPr (soluble; MW = 9,000); FPr (fructose induced HPr‐like protein (soluble; MW = 8,000). HPr and FPr are phosphorylated on the N‐1 position of a histidyl residue while all the others appear to be phosphorylated on an N‐3 position of a histidyl residue. These studies identify some previously unknown proteins of the PTS and show the phosphorylation of others, which although previously known, had not been shown to be phosphoproteins.
Immunological comparison of desmosomal components from several bovine tissues
Authors: Giudice George J. , Cohen Stephen M. , Patel Nipam H. , Steinberg Malcolm S.
Published: December 2004

A panel of monoclonal antibodies and conventional antisera directed against desmosomal proteins from bovine muzzle epidermis was used Io identify immunologically related proteins from two other bovine stratified squamous epithelia, cornea and esophagus. Desmosome‐enriched tissue fractions were prepared from epidermis, cornea, and esophagus. These tissue extracts were electrophoresed on sodium dodecyl sulfate (SDS)‐polyacrylamide gels, blotted onto nitrocellulose paper, and labeled using an indirect immunoperoxidase technique. Labeling with the conventional antisera demonstrates that each of the previously characterized epidermal desmosomal proteins or protein families has an immunologically cross‐reacting counterpart in cornea and esophagus. However, chemical differences between homologous desmosomal proteins in these three tissues have also been detected. The corresponding proteins in the different tissues have similar but not always identical apparent molecular weights. Moreover, tissue‐restricted antigenic determinants were detected in two of the desmosomal protein families using four monoclonal antibodies, each of which recognizes a distinct antigenic determinant.
Decreased activity of acetyl‐CoA carboxylase during chemically induced neutrophilic differentiation of human promyelocytic leukemia cells
Authors: Fischkoff Steven A. , Papuchis Gary C. , Nickols Wayne A.
Published: December 2004

In order to better understand the mechanism by which changes in the fatty acid composition of cellular lipids occur in leukemia cell lines induced to differentiate, the activity of the first enzyme of fatty acid biosynthesis, acetyl‐CoA carboxylase (EC 6.4.1.2) was measured in HL‐60 promyclocytic leukemia cells before, during and after treatment with compounds that induce these cells to mature to neutro‐phillike cells. After 24 h of exposure to dimethylsulfoxide, retinoic acid, or butyric acid, no morphological or biochemical (nitroblue tetrazolium reduction) evidence of differentiation occurred, but acetyl‐CoA carboxylase activity decreased 44, 44.5, and 49% respectively, compared to untreated cells. After 7 days of culture in the presence of these agents, 79, 83, and 72% of cells acquired the ability to reduce nitroblue tetrazolium (versus 15% of control cells) and enzyme activity decreased 92.7, 99.7, and 98%, compared to control cultures, with the three compounds respectively. Thus, some of the reported changes in fatty acid composition of leukemia cells with differentiation may arise, in part, from the depression of the de novo fatty acid biosynthetic pathway and the loss of acetyl‐CoA carboxylase activity may be a useful marker for neutrophilic differentiation in HL‐60 cells.
Protamine inhibits platelet derived growth factor receptor activity but not epidermal growth factor activity
Authors: Huang Jung San , Nishimura Junji , Huang Shuan Shian , Deuel Thomas F. , Deuel Thomas F.
Published: December 2004

Protamine sulfate blocked 125I‐PDGF binding to its specific physiological receptor on Swiss mouse 3T3 cells. Reduced 125I‐PDGF binding in the presence of protamine sulfate correlated directly with a protamine sulfate dose‐dependent decrease in the PDGF‐dependent incorporation of [3H]‐thymidine into 3T3 cells and a decreased PDGF‐stimulated tyrosine‐specific protein kinase activity in isolated membrane preparations of 3T3 cells. Protamine sulfate blocked 125I‐PDGF binding to simian sarcoma virus transformed cells (SSV‐NIH 3T3 and SSV‐NPl cells) and to nontransformed cells in a manner qualitatively identical to unlabelled PDGF. In contrast, protamine sulfate enhanced the specific binding of 125I‐EGF by increasing the apparent number of EGF receptors on the cell surface. The increase in 125I‐EGF receptor binding was not prevented by cycloheximide nor by actinomycin D. Protamine sulfate did not affect 125I‐EGF binding to membranes from 3T3 cells or the EGF‐stimulated 3T3 cell membrane tyrbsinc specific protein kinase activity, suggesting that protamine sulfate may have exposed a population of cryptic EGF receptors otherwise not accessible. Protamine sulfate was fractionated into four active fractions by Sephadex G‐50 gel filtration columns; the half maximum inhibition concentration of 125I‐PDGF binding to 3T3 cells of protamines I and II (MW ∼ 11,000 daltons and 7,000 daltons, respectively) is ∼ 0.4 μM. Protamine II (MW ∼ 4,800 daltons) was equally active (half maximum inhibition concentration ∼ 0.4 μM); protamine IV (MW ∼ 3,300 daltons) was substantially less active (half maximum inhibition concentration ∼ 2.8 μM).

These investigations have extended previous observations that protamine sulfate is a potent inhibitor of PDGF binding and establish that protamine sulfate blocks PDGF binding at the physiological receptor, preventing PDGF initiated biological activities. Protamine sulfate can be used as a reagent to separate the influence of PDGF and EGF on cells with high specificity and has been used to demonstrate that the receptors on simian sarcoma virus transformed 3T3 cells qualitatively respond identically to protamine sulfate as to unlabelled PDGF and are likely identical to those on nontransformed 3T3 cells.
Production of a monoclonal antibody directed against the nerve growth factor receptor from sympathetic membranes
Authors: Morgan Claudia J. , Bradshaw Ralph A.
Published: December 2004

Spleen cells from BALB/c mice immunized with a plasma membrane‐enriched fraction from rabbit sympathetic ganglia were fused with the mouse myeloma NS1. A hybrid clone was obtained that produced monoclonal antibody directed against the receptor for nerve growth factor (NGF). The antibody, identified as IgG, was able to immunoprecipitate solubilized NGF receptor in the presence or absence of bound NGF. The antibody bound specifically to sympathetic membranes with high affinity but did not affect the binding of 125I‐NGF to its receptor in sympathetic or sensory neurons or PC12 cells.
The differential distribution of beta tubulin mRNAs in individual mammalian brain cells
Authors: Griffin W. Sue T. , Alejos Michael A. , Cox Erica J. , Morrison Marcelle R.
Published: December 2004

It has been shown by in vitro translation of polyadenylated messenger RNAs (poly(A)+ mRNAs) that the mRNAs encoding both alpha and beta tubulin isotypes are present at much higher relative levels in the developing rat brain than they are in the adult [1], suggesting that the requirements for tubulin subunits vary with cell type and/or with the developmental stages of a particular cell type. The postnatally developing rat cerebellum, with its readily identifiable cell populations that perform the gamut of developmental tasks, is a suitable model for analyzing specific cellular mRNA distributions during development. In this report, by in situ hybridization techniques it is shown that, by comparison to total cellular poly(A)+ mRNA levels, there is relatively more of the total beta tubulin mRNAs in mitotically active external granule layer cells than in those in the internal granule layer. These results show that migration and differentiation of these granule cells is accompanied by a decrease in their beta tubulin mRNA levels relative to the levels in granule cells of the external granule cell layer. Furthermore, the relative levels of beta tubulin mRNA both in the prenatally formed Purkinje cells and the postnatally formed stellate cells are two to fourfold less than in the granule cells of the internal granule cell layer.
Purification and partial characterization of a liver cell proliferation factor called hepatopoietin
Authors: Goldberg Michel
Published: December 2004

The purification and partial characterization of a liver cell proliferation factor called hepatopoietin are described. Hepatopoietin was isolated from remnant livers or blood plasma of partially hepatectomized rats and purified approximately 13,000‐fold. The stokes radius was 2.65 ± 0.2 nm and the apparent molecular weight was calculated to be 38,000 ± 5,000 D. Hepatopoietin is a heat‐stable glycoprotein and is organ specific but species nonspecific. In vivo it stimulates about three to four times the DNA synthesis as well as the mitotic rate of the liver of normal rats after i.p. injection. Hepatopoietin is inactivated upon incubation with galactosidase or trypsin‐chymotrypsin.
Regulation of discoidin I gene expression in dictyostelium discoideum by cell‐cell contact and cAMP
Authors: Berger Edward A. , Bozzone Donna M. , Berman Marcia B. , Morgenthaler Jennifer A. , Clark Judy M.
Published: December 2004

We have previously presented evidence that cell‐cell contact is the normal developmental signal to deactivate discoidin I gene expression in D discoideum [Berger EA, Clark JM: Proc Natl Acad Sci USA 80:4983, 1983]. Here we provide genetic evidence to support this hypothesis by examining gene expression in a cohesion‐defective mutant, strain EB‐21, which enters the developmental program but is blocked at the loose mound stage, When this strain was developed in suspension, the cells remained almost entirely as single amoebae, unlike the wild type, which formed large multicellular aggregates. In both strains, discoidin I mRNA levels were low in vegetative cells but rose sharply during the first few hours of development. However, the peak level reached at 8 hr in EB‐21 exceeded that observed in wild type, and while the level declined markedly over the next few hours in wild type, it remained highly elevated in the mutant. Thus, there was a correlation between the inability of EB‐21 to form normal cell‐cell contacts and its deficiency in inactivating discoidin I gene expression.

Previous studies from several laboratories, including this one, have demonstrated that exogenously added cAMP can block or reverse the changes in gene expression normally seen upon cell disaggregation. This has led us to propose that cAMP serves as a second messenger regulating the expression of contact‐regulated genes. Here we provide additional support for this hypothesis. Intracellular cAMP levels rapidly dropped several‐fold when wild type tight cell aggregates were disaggregated and remained low as the cells were cultured in the disaggregated state, Furthermore, overexpression of discoidin I mRNA late in development in EB‐21 was corrected by addition of high concentrations of cAMP. These results are consistent with a second messenger function for cAMP in the contact‐mediated regulatory response, and they indicate that the cAMP response machinery for discoidin I gene expression is capable of functioning in the cohesion‐defective EB‐21 strain.
Deposition of type X collagen in the cartilage extracellular matrix
Authors: Cancedda Ranieri , Capasso Olga , Castagnola Patrizio , Descalzi‐Cancedda Fiorella , Quarto Natalina
Published: December 2004

In cultured chick embryo chondrocytes, type X collagen is preferentially deposited in the extracellular matrix, the ratio between type II and type X collagen being about 5 times higher in the culture medium than in the cell layer. When the newly synthesized collagens deposited in slices from the epiphyseal cartilage of 17‐day‐old embryo tibiae were isolated, type X collagen was always the major species. In agreement with this result the mRNA for type X collagen was the predominant mRNA species purified from the same tissue. When the total collagen (unlabeled) deposited in the epiphyseal cartilage was analyzed, it was observed that type X collagen represented only 1/15 of the type II collagen recovered in the same preparation. The possible explanations for these differences are discussed.
Interaction of the insulin receptor kinase with serine/threonine kinases in vitro
Authors: Haring Hans U. , White Morris F. , Kahn C. Ronald , Ahmad Zafeer , DePaoli‐Roach Anna A. , Roach Peter J.
Published: December 2004

Insulin causes rapid phosphorylation of the β subunit (Mr = 95,000) of its receptor in broken cell preparations. This occurs on tyrosine residues and is due to activation of a protein kinase which is contained in the receptor itself. In the intact cell, insulin also stimulates the phosphorylation of the receptor and other cellular proteins on serine and threonine residues. In an attempt to find a protein that might link the receptor tyrosine kinase to these serine/threonine phosphorylation reactions, we have studied the interaction of a partially purified preparation of insulin receptor with purified preparations of serine/threoine kinases known to phosphorylate glycogen synthase. No insulin‐dependent phosphorylation was ob served when casein kinases I and II, phosphorylase kinase, or glycogen synthase kinase 3 was incubated in vitro with the insulin receptor. These kinases also failed to phosphorylate the receptor. By contrast, the insulin receptor kinase catalyzed the phosphorylation of the calmodulin‐dependent kinase and addition of insulin in vitro resulted in a 40% increase in this phosphorylation. In the presence of calmodulin‐dependent kinase and the insulin receptor kinase, insulin also stimulated the phosphorylation of calmodulin. Phosphoamino acid analysis showed an increase of phosphotyrosine content in both calmodulin and calmodulindependent protein kinase. These data suggest that the insulin receptor kinase may interact directly and specifically with the calmodulin‐dependent kinase and calmodulin. Further studies will be required to determine if these phosphorylations modify the action of these regulatory proteins.
Phenazine methosulfate stimulation of ouabain‐sensitive Rb+ uptake by HeLa cells: Effects of respiratory inhibitors, anaerobiosis, and ascorbate
Authors: Ikehara Toshitaka , Yamaguchi Hisao , Hosokawa Keiko , Kaku Masayuki , Miyamoto Hiroshi
Published: December 2004

Phenazine methosulfate (PMS) stimulates ouabain‐sensitive Rb+ uptake by HeLa cells. This stimulation cannot be attributed to the effect of the dye on the intracellular Na+ or ATP content. Respiratory inhibitors, such as 5 mM NaCN and 5 mM rotenone, and anaerobic conditions enhance the stimulation of Rb+ uptake by PMS. Cellular respiration is stimulated, but lactate production is reduced in the presence of PMS, irrespective of the presence of respiratory inhibitors. Cellular NADH is oxidized markedly on addition of PMS plus inhibitors, but it is not affected by addition of the inhibitors only. In the presence of a high concentration of PMS, PMS‐stimulated ouabain‐sensitive Rb+ uptake is inhibited by addition of ascorbate. From these results it is concluded that Na/K‐pump activity is closely related to the cellular redox state.
Role of protein kinase C in transmembrane signaling
Authors: Takai Yoshimi , Kaibuchi Kozo , Tsuda Terutaka , Hoshijima Masahiko
Published: December 2004

Many extracellular signals elicit Ca2+ mobilization and diacylglycerol formation in their target cells. Diacylglycerol is derived from the receptor‐linked phosphoinositide turnover and serves as a second messenger for the activation of protein kinase C in the presence of Ca2+ and phosphatidylserine. Unique diacylglycerols such as 1‐oleoyl‐2‐acetyl‐glycerol, which activate intracellular protein kinase C when added to intact cells, have been synthesized. Tumor‐promoting phorbol esters substitute for such diacylglycerols and directly activate protein kinase C in both intact cell and cell‐free systems. Under appropriate conditions, the synthetic diacylglycerols and phorbol esters induce protein kinase C activation without Ca2+ mobilization, whereas Ca2+ ionophore A23187 induces Ca2+ mobilization without protein kinase C activation. Using these substances, we have obtained evidence that both protein kinase C and Ca2+ are involved in and play a synergistic role in exocytosis, cell division, and other cellular functions. In this article, the role of protein kinase C in transmembrane signaling is discussed.
Molecular mechanisms of cytotoxicity mediated by Entamoeba histolytica: Characterization of a pore‐forming protein (PFP)
Authors: Young John Ding‐E , Cohn Zanvil A.
Published: December 2004

Entamoeba histolytica is the human pathogen responsible for amebiasis. This infection is characterized by an invasive enteric illness that may spread to multiple organs. The parasite E histolytica may now be cultivated in vitro, with Diamond's axenic medium [1]. In culture, this protozoan remains cytolytic to a variety of cell types, including neutrophils and macrophages (reviewed in [2]). The mechanism(s) involved in the expression of this potent cytolysis remain(s) unclear. Previous studies from several laboratories have suggested that the cell killing mediated by amoeba is dependent on intimate contact of amoeba with the target cell membrane [3–9]. Following contact, the amoeba readily ingests the target cell (Fig. 1A). However, more recent cinemicroscopic and kinetic studies [8,9] (see also Fig. 1B) indicate that the cytolysis mediated by amoeba may occur prior to phagocytosis, raising the possibility of an extracellular cytolytic event triggered by surface contact.

Previous work from this laboratory has described the properties of a highly enriched plasma membrane fraction and surface polypeptides from axenically grown E histolytica [10,11]. Studies from this laboratory on its extensive vacuolar apparatus and its role in pinocytosis and intracellular acidification have also been published [12,13]. Here, we review some recent evidence for the isolation and characterization of a pore‐forming protein (PFP) extracted from this protozoan, which may be closely related to the killing of target cells mediated by pore‐forming proteins of the immune system (the complement cascade as well as proteins extracted from granules of different immune cells [Young et al, in preparation]), which may thereby suggest a very similar and general mechanism of cell‐mediated cytotoxicity.