bluuebunny/crossref_metadata_2025 huggingface dataset:
Improved fire safety of composites for naval applications
Authors: Sorathia Usman , Rollhauser Charles M. , Hughes W. Allen
Published: May 2005

This study is based on the use of integral, hybrid thermal barrier to protect the core of the composite structure. Thermal barrier treatments evaluated in this study include ceramic fabric, ceramic coating, intumescent coating, hybrid of ceramic and intumescent coating, silicone foam, and phenolic skin. The composite systems evaluated in combination with thermal barrier treatments included glass/vinyl ester, graphite/epoxy, graphite/bismaleimide, and graphite/phenolic. All configurations were tested for flammability characteristics. These included smoke density and combustion gas generation (ASTM E‐662), residual flexural strength (ASTM D‐790), heat release rate, and ignitability (ASTM E‐1354). ASTM E‐662 test method covers the determination of specific optical density of smoke generated by solid materials. ASTM D‐790 test method covers the determination of flexural properties of composite materials in the form of rectangular bars. ASTM E‐1354 (cone calorimeter) covers the measurement of the response of materials exposed to controlled levels of radiant heating with or without an external ignitor, and is used to determine the ignitability, heat release rates, mass loss rates, effective heat of combustion, and visible smoke development. Without any fire barrier treatments, all composite systems evaluated in this study failed to meet ignitability and peak heat release requirements of MIL‐STD‐2031 (SH) at radiant heat fluxes of 75 and 100 kW m−2, respectively. Intumescent coating and a hybrid system consisting of intumescent coating over ceramic coating were the most effective fire barrier treatments for composite systems evaluated in this study. Using either of these treatments, all composite systems met the ignitability requirements of 90 and 60 at 75 and 100 kW m−2, respectively. Except for glass/vinyl ester, all systems also met the peak and average heat release requirements of MIL‐STD‐2031 (SH) at radiant heat fluxes of 25, 75, and 100 kW m−2, respectively.
Note: Fire‐retardant treatment of roofing thatch
Authors: Eboatu A. N. , Birnin‐Kebbi F. , Shehu D.
Published: May 2005

The double salt calcium phosphate–calcium sulphate monohydrate, hereafter referred to as fertilizer, was used to impregnate some grass commonly used for roofing houses. It was found that this treatment significantly changed the thermal characteristics of the material. Reasons are adduced to explain these observations.
Oxygen index: Correlations to other fire tests
Authors: Weil Edward D. , Patel Navin G. , Said M. M. , Hirschler Marcelo M. , Shakir Saleem
Published: May 2005

An investigation has been carried out of the limiting oxygen index (LOI) test. A review of the literature shows that, although there is abundant information on the test, it is not clear that its results correlate well with those of any other test, or indeed with those of real fires. Theoretical considerations indicate that the test could be improved by using it with bottom ignition rather than with the standard top ignition. A number of materials were tested in the cone calorimeter and in the LOI, and various correlations were attempted. In general, correlations between some of the cone calorimeter properties measured and the inverse of the LOI made sense. These correlations were not, however, sufficiently sensitive, even when investigating small effects on a single base polymer system, to justify using the LOI as a proxy for the cone in any way. The LOI is likely to continue to be used extensively. This work suggests that quality control and, possibly, mechanistic or other flame‐retardant additive studies, are its only applications where the results can be justified.
An experimental facility for determination of steady flame spread rate of materials employing the Quasi‐stationary flame front technique
Authors: Bhatnagar Subodh Kumar , Varshney B. S. , Mohanty B.
Published: May 2005

An experimental facility based on the Quasi‐stationary Flame Front Technique for determination of steady flame spread rate of materials at discrete levels of external radiant heat flux was developed. The method employs an external radiant heat source in front of which an element of a specimen of the material is positioned at a location corresponding to the desired level of external radiant heat flux. A specimen movement assembly, which can be operated manually, was designed for moving the specimen towards the stationary external radiant heat source such that the flame front could be maintained quasi‐stationary. The experimental technique employed is simple in operation yet is capable of yielding reliable flame fornt displacement–time data. In the paper the design considerations of the experimental facility, details of its components, calibration and typical experimental results obtained are presented.
Fire performance of fire‐retardant wood fiberboard ceiling tile
Authors: Zicherman J. B. , Allard D. L.
Published: May 2005

Wood fiberboard‐based, cellulose ceiling tiles have been used for many years. While various fire‐retardant technologies have been developed to reduce the surface flammability of these products to acceptable levels, questions of their suitability for use due to their intrinsic fuel value and the impact of attachment methods used on fire performance have been raised from time to time. This paper reviews the history of these products from a fire‐performance perspective and presents materials property data on surface flamespread, thermal conductivity and ignition phenomena. In addition, large‐scale room fire test results are presented including compartment tests conducted on a variety of assemblies (including those installed with mastic construction adhesives) according to ASTM E 603—Standard Guide for Room Fire Experiments.
An attachment for use with the NBS smoke density chamber for measurement of smoke obscuration at different orientations
Authors: Hirschler Marcelo M.
Published: May 2005

The NBS smoke density chamber (ASTM E662) is the most popular test instrument used to measure smoke obscuration. In its standard use, it can accommodate only samples in the vertical orientation. In this work, the smoke generated by 12 materials was measured in the smoke chamber in the normal way and by using a proposed attachment, with a dual‐burner system which can be oriented both horizontally and vertically. Results obtained were different for many of the materials, due particularly to melting characteristics of some of them, which then led to inaccurately small smoke values. Most of the materials were also tested in the cone calorimeter, which gave the same trends (albeit with a mediocre correlation) as the smoke chamber in the horizontal orientation. The correlation between cone calorimeter results and vertical orientation (traditional or dual‐burner) results in the smoke chamber was virtually non‐existent. This suggests that the use of the NBS smoke chamber in a horizontal orientation may result in it yielding more meaningful data.
Plasma MHPG and AMDP depression relations, evolution and drug effect in a follow‐up study of depressed patients
Authors: Karege F. , Bovier Ph. , Gaillard J.‐M. , Tissot R.
Published: May 2005

Plasma MHPG levels and AMDP rating score were measured in depressed patients before treatment, and a follow‐up study was performed during the next 3 months of drug therapy to detect possible relationships between the parameters. Before treatment, MHPG levels were moderately lower in depressed than in age‐ and sex‐matched normal subjects. Bipolar depressed patients presented the lowest values. In the three diagnostic groups (DSM‐III), antidepressant treatment resulted in a significant decrease of mean levels in unipolar and dysthymic depressed, but not in bipolar depressed patients. When the type of antidepressant was considered, imipramine (IMI)‐ or desipramine (DMI)‐treated patients, but not fluvoxamine (FLU)‐treated, also decreased their mean values of MHPG, with minor difference between improved and non‐improved patients. However, when patients were grouped according to their pattern groups (low (LL), high (HL), or normal (NL) baseline MHPG levels), interesting information emerged: improvement of clinical state of patient (i.e. 60 per cent of AMDP baseline reduction) resulted in ‘normalization’ of erratic values (HL and NL) whatever the treatment, while in non‐improved patients such evolution was not observed. In the latter group, change in MHPG levels was only drug‐related (decrease in IMI–DMI‐treated and no change in FLU‐treated values). Results suggest that mechanisms of buffering NA activity were lost in endogenous depression and restored in patients responding to treatment.
Dopamine depletion hypothesis of cocaine dependence: A test
Authors: Gill K. , Gillespie H. K. , Hollister L. E. , Davis C. M. , Peabody C. A.
Published: May 2005

Measurements of plasma homovanillic acid (HVA), plasma 3‐methoxy‐4‐hydroxyphenylglycol (MHPG), serum prolactin and Hamilton Depression Rating Scale (HDRS) scores were made in 21 cocaine‐dependent patients seeking inpatient treatment. These measurements were obtained within 1–3 days of the last dose of cocaine and were repeated after 10–20 days of abstinence from cocaine. Abnormal values on any of the biochemical measurements were unusual and showed no convincing evidence of dopamine or norepinephrine depletion. Ten patients had significant HDRS scores on admission which decreased by 50% or more during hospitalization without specific treatment. The controversy over whether chronic exposure to cocaine depletes dopamine remains unsettled. Howevr, it is more likely that down‐regulation of postsynaptic dopamine receptors is the major consequence of such exposure.
Is viloxazine an antidepressant? A placebo‐controlled double‐blind study in major depressive disorder presenting in a general hospital
Authors: Thompson C. , Isaacs G.
Published: May 2005

Viloxazine was one of the first of the ‘second‐generation’ antidepressants. Its relative lack of cardiotoxic, anticholinergic, sedative and seizure‐inducing adverse effects suggested its use as an antidepressant in general hospitals where tricyclic antidepressants might be frequently contraindicated. We conducted a double‐blind trial of 300 mg viloxazine against placebo in 43 patients with major depressive disorder. The placebo‐treated group showed a slightly, but not significantly, greater improvement in depression scores using observer and self‐rating scales over those using viloxazine. A review of previous placebo‐controlled studies of viloxazine offers little support to its use as an antidepressant.
A short‐term open trial of clomipramine in the treatment of patients with panic attacks
Authors: Judd F. K. , Burrows G. D. , Marriott P. F. , Farnbach P. , Blair‐West S. , Norman T. R.
Published: May 2005

Clomipramine was used to treat 14 patients with panic attacks. Diagnosis was made according to DSM‐III criteria for agoraphobia with panic attacks or panic disorder uncomplicated. An open evaluation of the drug over an 8‐week treatment period was conducted. A total of 10 patients completed the study. Clomipramine was effective in reducing the mean number of panic attacks, the greatest response being observed in the first 2 weeks of treatment. Findings on all outcome measures showed that clomipramine was also effective in alleviating depression secondary to panic attacks, non‐specific aspects of anxiety and improving phobic avoidance. There was a suggestion that responders to treatment received lower doses of clomipramine than non‐responders. Further studies are required to evaluate this issue and the role of clomipramine in the treatment of panic disorders.
Acute extrapyramidal reactions following lithium and sulpiride co‐administration: Two case reports
Authors: Dinan Timothy G. , O'Keane Veronica
Published: May 2005

Two case reports are presented in which lithium and sulpiride were used jointly in patients with affective disorder. In both cases significant extrapyramidal reactions occurred. The reactions were successfully treated by withdrawing the drug combination. It is suggested that the adverse events relate to the mechanism of action of sulpiride which, unlike other neuroleptics, requires sodium to bind to the dopamine receptor. Lithium may substitute for sodiumenhancing sulpiride binding.
Intraosseous anchorage of the carbon fiber composite ligament by bony ingrowth
Authors: Boss Jochanan H. , Shajrawi Ibrahim , Mendes David G.
Published: May 2005

It is common experience that carbon fiber braids, which are passed through osseous tunnels, are not incorporated by osteointergration. Rather, they are separated from the boy walls of the tunnels by a granulomatous–cicatrizing interface membrane. In the exceptional case, however, Bony ingrowth into the braid occurs without an intervening soft tissular layer. Bony ingrowth may be contingent on the stability of the carbon fiber braid within the osseous tunnel.
Nanocrystalline epsein–barr virus decoys
Authors: Kossovsky Nir , Gelman Andrew , Sposler Edward , Millett David
Published: May 2005

A novel biotechnology is introduced by way of the successful synthesis of nanocrystalline Epstein–Barr virus (EBV) decoys having specific in vivo immunogenie activity. Assembled from ultrafine suface modified tin oxide and purified DNA‐free isolated EBV envelope proteins, the decoys consisted of >150 nm units whose electophoretic mobilities were similar to whole EBV; whose outer coats were strongly immunoreactive with murine monoclonal anti‐EBV antibodies; and which elicited immunospecific niutralizing anti‐EBV antibodies in the rabbit. The development of this carier techonology for vaccine preparations is suggested.
In vitro analysis of the effects of biomaterial adherence on a Staphylococcus epidermidis strain's sensitivity to cephaloridine
Authors: Oga Masayoshi , Arizono Tuyoshi , Sugioka Youichi , Naylor Paul T. , Myrvik Quentin N. , Gristina Anthony G.
Published: May 2005

This study examined the effects biomaterial adherence had on Staphylococcus epidermidis‐46 morphology and sensitivity to the antibiotic cephaloridine. Polymethylmethacrylate (PMMA) discs served as the biomaterial substratum in this study. Suspension cultures of SE‐46 at 108 CFU/mL were allowed to adhere to PMMA discs for 2, 6, or 12 h prior to exposure to cephaloridine at 250 μg/mL, which is 500 times greater than the MIC of 0.5 μg/mL. After a 24‐h exposure to the antibiotic viable bacteria adherent to the disc were removed and counted. Those data revealed that at shorter adherence times a larger percentage of the adherent organism were erradicated by antibiotic exposure, 83.6%versus 15.6%for 2‐h and 12‐h adherencetimes, respectively. Although a significant percent of the organisms were killed with short adherence times, the organism still persisted in the face of high concentrations of cephaloridine. Scanning electron micrographs of organism adherent for 2 and 12 h revealed distinct morphological changes in the extracellular matrix indicating increased matrix production with longer adherence. Thus, these data reveal that adherence to biomaterials provides a protected environment for the bacteria and the time an organism is adherent to a biomaterial surface prior to antibiotic exposure can also increase the organism's resistance to antibiotics.
Burst testing of condoms. I. Basic features of the force‐deformation curve of latex‐rubber condoms
Authors: Wilson T. W. , Andrady A. L.
Published: May 2005

Inflation of a rubber condom involves biaxial deformation of the material which can be modeled by the use of an appropriate strain‐energy function. Force versus deformation data for uniaxial extension of strips of condoms were used to determine the parameters for Ogden's form of a strain‐energy function. These parameters were then used to fit experimentally obtained burst test data to a stress‐strain equation formulated for inflation of condoms in a burst test. Experimental data on inflation of condoms agree well with theoretical curves verifying the applicability of the biaxial stress‐strain equation to the particular strain‐energy function on which it is based.
Distribution of bacterial cells within fibrous air sterilization filters
Authors: Aiba Shuichi , Yamamoto Akira
Published: May 2005

Applying radio‐isotope 32P, the distribution of bacterial cells retained within glass‐fibre air sterilization filters was measured. In particular, the time‐dependence of the radial as well as the longitudinal distribution was studied. The collection efficiency of glass‐fibre was obtained and the experimental result was compared with a theoretical value based upon the sum of interception, inertia and diffusion. Discrepancies could not be accounted for and are similar to those in the literature. An equation was proposed for the estimation of air filter life. This was not completely verified but leads to some suggestive results.
Composition of a domestic sewage
Authors: Painter H. A. , Viney M.
Published: May 2005

An analysis of the organic constituents of whole, domestic sewage was made by analysing four physically separated fractions. Settlement, centrifuging and filtration were used to obtain one liquid and three solid fractions. Concentration of the filtrate was achieved by freeze‐drying with only minor changes in composition. The average concentration of organic carbon in fresh, whole domestic sewage was 310 p.p.m., of which about 70 per cent was in suspension. Eight classes of compounds were found, on analysis, to comprise about 75 per cent of the organic carbon in whole sewage and of the soluble organic carbon 80 per cent was distributed between five groups. Using chromatographic methods the concentrations of four volatile acids were determined and the presence of other acids was detected. Similarly, seven of the soluble sugars and eight present in hydrolysed suspended solids have been identified. The probable nature of some of the compounds unaccounted for is discussed.
An attempt to determine discriminate use of hydrogen isotopes by bacteria
Authors: Linday E. Margery , Syrett P. J.
Published: May 2005

The hydrogenase system of Hydrogenomonas facilis could be induced by either hydrogen or deuterium and the rate of deuterium uptake by the induced cells was the same as that of hydrogen.

An attempt has been made to detect discriminate use of hydrogen and deuterium by bacteria. No discrimination could be detected during hydrogenation of methylene blue by Escherichia coli, under the experimental conditions.
Mass propagation of algae for photosynthetic gas exchange
Authors: Gaucher Thomas A. , Benoit Richard J. , Bialecki Adolph
Published: May 2005

Engineering data on the design and operation of algal culture systems for photosynthetic gas exchange are virtually non‐existent. The authors have conducted intermediate and definitive level engineering studies to characterize algal systems—with a view to extrapolating to larger‐scale systems for life support in closed spaces.

Light intensity, carbon dioxide concentration, and dilution rate were the principal parameters used to control the photosynthetic rate and, consequently, oxygen production. Carbon dioxide absorption rate, equilibrium density, and cellular growth rate were also investigated.

It was found that: (1) properly jacketed high intensity, incandescent lamps provided a suitable light source for growing algae; and (2) physiologically safe (0·5 per cent) concentrations of carbon dioxide produced growth comparable to that obtained at higher concentrations.

A dilution rate of nearly 0·1 volume change per hour produced the best oxygen yield (2·41 × 10−3 lb/h) for the definitive system. Maximum cell doubling time was 5·1 h. The highest culture density attained was 5·9 mm3/ml, and the maximum dry weight algae yield was 3·0 × 10−3 lb/h.
A method for the preparation of undigested bacterial cell walls
Authors: Yoshida A. , Hedén C.‐G. , Cedergren B. , Edebo L.
Published: May 2005

The combination of low‐temperature disintegration with gradient and pile centrifugation makes possible the preparation of bacterial cell walls under conditions preventing digestion.
The disintegration of yeast with dry ice and some properties of the extract
Authors: v. Hofsten Bengt , Tjeder Anders
Published: May 2005

A simple procedure for the disintegration of yeast cells, by which litre quantities of cell extract (approximately 11 per cent dry weight) may be obtained, is described. The fresh yeast cake is treated with dry ice in a high speed electric homogenizer after which it is left to thaw out at 0°. No addition of buffer has to be made, and the cell juice obtained after centrifugation of the resulting slurry appears to contain different subcellular particles and various enzymes in a relatively native state.

When the extract is incubated at higher temperatures, proteolysis will rapidly change the electrophoretic and enzymatic properties, which indicates that procedures involving autolysis may be dangerous when information about the chemical composition of the native enzymes is desired.
Die technische Herstellung von klinischem dextran durch gelenkte synthese in wachsender Kultur
Authors: Behrens U. , Ringpfeil M. , Brückner D. , Fröhlich M. , Krüger K. , Thiel H. , Torporski W.
Published: May 2005

A process is described for the production of a specific‐molecular‐weight dextran, e.g. clinical dextran, by using a modified form of controlled synthesis. The synthesis is carried out directly in a medium containing appropriate amounts of sucrose and low‐molecular‐weight dextran after inoculation with a culture of actively growing bacteria. The importance of an inoculum substantially freed from substances affecting the synthesis of dextran is demonstrated. The technique appears to offer a decided advantage over other well‐known procedures. Technical details of the process and equipment are given.
Volume increase of wheat kernels accompanying absorption of liquid water
Authors: Chung Do Sup , Fan Liang‐Tseng , Shellenberger John A.
Published: May 2005

The purposes of this investigation were to determine the relationship between weight and volume increases which take place when wheat kernels are immersed in water, to develop an equation for the volume increase, and to test experimentally its validity.

It was shown that the volume increase was practically equal to the weight increase divided by the fluid density. In view of this, the following equation was obtained by analogy to the diffusion equation derived by Becker.1

where 1 − V̄ is the relative volume increase, and Dv is the coefficient of volume increase.

The average coefficients of volume increase are given by the Arrhenius relation as:

The results obtained in this investigation provide useful information for designing the steeping vessels.
Differential repair and replication of damaged DNA in ribosomal RNA genes in different CHO cell lines
Authors: Wauthier Eliane L. , Hanawalt Philip C. , Vos Jean‐Michel H.
Published: May 2005

We studied the repair of psoralen adducts in the pol I–transcribed ribosomal RNA (rRNA) genes of excision repair competent Chinese hamster ovary (CHO) cell lines, their UV sensitive mutant derivatives, and their UV resistant transformants, which express a human excision repair gene. In the parental cell line CHO‐AA8, both monoadducts and interstrand crosslinks are removed efficiently from the rRNA genes, whereas neither adduct is removed in the UV sensitive derivative UV5; removal of both adducts is restored in the UV resistant transformant CHO‐5T4 carrying the human excision repair gene ERCC‐2. In contrast, removal of psoralen adducts from the rRNA genes is not detected in another parental CHO cell line CHO‐9, neither in its UV sensitive derivative 43°3B, nor in its UV resistant transformant 83°G5 carrying the human excision repair gene ERCC‐1. In contrast to such intergenomic heterogeneity of repair, persistence of psoralen monoadducts during replication of the rRNA genes occurs equally well in all CHO cell lines tested. From these data, we conclude that: (1) The repair efficiency of DNA damage in the rRNA genes varies between established parental CHO cell lines; (2) the repair pathways of intrastrand adducts and interstrand crosslinks in mammalian cells share, at least, one gene product, i.e., the excision repair gene ERCC‐2; (3) replicational bypass of psoralen monoadducts at the CHO rRNA locus occurs similarly on both DNA strands.
In vitro depolymerization dynamics of brain endogenous microtubules
Authors: López Luis A. , Mayorga Luis S. , Bertini Francisco
Published: May 2005

A subcellular fraction containing fragments of endogenous microtubules stabilized in 50% glycerol was separated by diferential centrifugation of rat brain homogenates. The pellets were suspended in glycerol‐deficient media, and microtubule depolymerization was monitored by measuring the decrease of sedimentable tubulin. Concomitantly, the number and size of microlubules in the suspensions were followed via electron microscopy. Depolymerization was accompanied by a proportional decrease in the number of microtubules, whereas the average size did not change significantly. After approximately 20 min, a subpopulation of microtubules became stable and did not suffer further depolymerization. These results indicate that upon dilution some microtubules completely depolymerize, whereas others remain stable in the glycerol‐deficient medium. The degree of depolymerization depended on both the volume of the resuspension media and on the final glycerol concentration. The results suggest that the depolymerization of the remaining microtubules is prevented by stabilizing factors released from depolymerizing microtubules. Tubulin dimers are not one of these factors, since depolymerization was not altered by the addition ofcolchicine or by changing the concentration of free tubulin in the medium.
Retransformation of a revertant cell line with the adenovirus E1 oncogenes and vanadate
Authors: Dessureault Jean , Weber Joseph M.
Published: May 2005

We have isolated a revertant cell line (G5) from an adenovirus transformed rat cell line (F4) which failed to express the integrated viral oncogenes. To determine whether the reversion mutation was acting in cis or trans the G5 cells were co‐transfected with an E1 gene bearing expression plasmid and a neomycin photransferase bearing plasmid. 0418‐resistant colonies were picked and shown to express the E1 proteins and to be tumorigenic. This re‐transformation could be partially mimicked by treatment with vanadate, an inhibitor of phosphotyrosine phosphatases. These results show that the continued presence of the E1 proteins was required to maintain the transformed phenotype, and that the reversion mutation was a cis‐acting event affecting directly the integrated E1 genes.
Clustering of sequential enzymes in the glycolytic pathway and the citric acid cycle
Authors: Beeckmans Sonia , Van Driessche Edilbert , Kanarek Louis
Published: May 2005

In recent years, evidence has been accumulating that metabolic pathways are organized in vivo as multienzyme clusters. Affinity electrophoresis proves to be an attractive in vitro method to further evidence specific associations between purified consecutive enzymes from the glycolytic Pathway on the one hand, and from the citric acid cycle on the other hand. Our results support the hypothesis of cluster formation between the glycolytic enzymes aldolase, glyceraldehydephosphate dehy‐drogenase, and triosephosphate isomerase, and between the cycle enzymes fumarase, malate dehydrogenase, and citrate synthase. A model is presented to explain the possibility of regulation of the citric acid cycle by varying enzyme‐enzyme associations between the latter three enzymes, in response to changing local intramitochondrial ATP/ADP ratios.
Exposure of perfused liver to hypotonic conditions modifies cellular nitrogen metabolism
Authors: Häussinger D. , Lang F.
Published: May 2005

Isolated livers were exposed to hypotonic perfusates. As shown previously, this hypotonic challenge leads to initial cell swelling, followed by volume regulatory ion fluxes, largely restoring cell volume within approximately 6 min. However, the hepatocyte is left in an altered metabolic state, which is characterized by marked stimulation of hepatic glutamine uptake and degradation and transient release of glutamate from the liver. Urea formation from glutamine and alanine is stimulated, whereas hepatic ammonia uptake and utilization for urea and glutamine synthesis decreases. These observations reveal a hitherto unrecognized factor modulating hepatic function during intestinal absorption.
Protein synthesis in embryonic tissues during mouse postimplantation development
Authors: Murach Karl‐Friedrich , Frei Monika , Gerhäser Dieter , Illmensee Karl
Published: May 2005

Mouse embryos of the NMRI strain between the 7th and 9th day of gestation were isolated from the uterus and dissected into the various tissue derivatives in order to investigate newly synthesized proteins during morphogenesis. The day 7 embryo was fragmented into trophoblast and ectoplacental cone, distal and proximal endoderm, extraembryonic and embryonic ectoderm. The day 8 and day 9 embryos were divided into trophoblast and placental anlage, yolk sac, amnion, and allantois, as well as cranial, central, and caudal embryonic tissue. The intact embryos were incubated in Dulbecco's minimum essential medium in the presence of 35S‐methionine for 4 h, then dissected into the various fragments, and further processed for two‐dimensional gel electrophoresis. Protein synthesis of the isolated tissue derivatives was analyzed and compared for the three developmental stages. Concerning the proteins with isoelectric points in the range of 4.5 to 8.0 and molecular weight ratio (Mr) values between 20,000 and 200,000, we found several significant quantitative and qualitative differences in the various tissue fragments. In addition, we observed further quantitative and qualitative differences in protein synthesis during the postimplantation period investigated. We propose that the differences reflect some of the cell lineage‐ and developmental stage‐specific changes in gene expression during early mammalian differentiation.
Control of expression and maturation of epidermal growth factor receptor
Authors: Das Manjusri , Kesavan Prabakaran , Khire Jayant
Published: May 2005

Epidermal growth factor (EGF)‐receptor is a 170 kDa transmembrane glycoprotein that contains a ligand‐binding external domain, and a catalytically active cytoplasmic region. The expression of this receptor as well as a 100 kDa homolog that contains only the external domain is enhanced by the ligand EGF. EGF acts at transcriptional and post‐transcriptional levels. To dissociate these pre‐translational effects and the effects of EGF on receptor polypeptide synthesis from these on receptor export, pulse‐chase experiments were conducted. These studies indicate that EGF stimulates post‐translational transport and processing of the receptor, and this stimulation can occur in the absence of new protein synthesis. Other studies show that EGF accelerates at least two slow events in receptor maturation–the deoxynojirimycin sensitive processing in endoplasmic reticulum (ER) and the swainsonine sensitive processing in Golgi. The results suggest that EGF may influence one or more of the rate determining steps that control receptor export from ER, and this may represent yet another aspect of EGF action that contributes to the positive regulation of EGF‐receptor protein expression.
Monoclonal antibody 425 inhibits growth stimulation of carcinoma cells by exogenous EGF and tumor‐derived EGF/TGF‐α
Authors: Rodeck Ulrich , Williams Noel , Murthy U. , Herlyn Meenhard
Published: May 2005

Carcinoma cells frequently coexpress transforming growth factor (TGF)‐α and its receptor, the epidermal growth factor (EGF) receptor, implicating an autocrine function of carinoma‐derived TGF‐α. Using a monoclonal antibody (425) to the EGF‐receptor, we investigated the role of exogenous and tumor cell‐derived EGF/TGF‐α mitogenic activities in proliferation of cell lines derived from solid tumors. Monoclonal antibody 425 was chosen for these studies because it inhibits binding of EGF/TGF‐α to the EGF‐receptor and effectively blocks activation of the EGF‐receptor by EGF/TGF‐α. Seven malignant cell lines originating from carcinomas of colon, pancreas, breast, squamous epithelia, and bladder expressed surface EGF‐receptor and secreted EGF/TGF‐α‐like mitogenic activities into their tissue culture media. All cell lines were maintained in a defined medium free of exogenous EGF/TGF‐α. EGF and TGF‐α added to the culture medium stimulated proliferation of five cell lines to comparable levels. EGF/TGF‐α‐dependent proliferation was significantly reduced by addition of MAb 425 to culture media. In addition, monoclonal antibody 425 reduced proliferation of the five EGF/TGF‐α responsive cell lines in the absence of exogenous EGF/TGF‐α. Antiproliferative effects induced by monoclonal antibody 425 were reversible and could be overcome by addition of EGF to culture media. Our results indicate that tumor‐derived EGF‐receptor‐reactive mitogens can promote proliferation of carcinoma cells in an autocrine fashion.
Biochemical changes associated with the mechanism controlling superoxide radical formation in the aging rotifer
Authors: Sawada Masaaki , Carlson John C.
Published: May 2005

Levels of the superoxide radical (SOR) and lipid peroxides were measured and found to increase during aging in the short‐lived rotifer, Asplanchna brightwelli. Life‐span was altered by changes in environmental temperature, absence of light, diet restriction, exposure to ultraviolet radiation, and addition of vitamin E to the diet. Each of the conditions that lengthened life‐span decreased SOR and lipid peroxide levels, and each condition that shortened life‐span increased levels of SOR and lipid peroxides. Additional experiments indicated that on the third day of age, there was a significant increase in Ca2+ uptake and phospholipase A2 activity in membrane samples and an elevation in superoxide dismutase and catalase activity in rotifer homogenates. In addition, SOR concentration was inhibited by the addition of bromophenacyl bromide and indomethacin to membrane samples. By day 5 there was also a significant increase in the lysosomal enzyme, α‐mannosidase. The results of this study indicate that levels of the SOR and lipid peroxides are coupled to rotifer life‐span and that activation of phospholipase A2 may contribute to the elevation of these agents in older animals.
Expression of a 64 kD adipocyte‐specific plasma membrane protein in genetically lean but not obese porcine adipocytes
Authors: Killefer John , Hu C. Y.
Published: May 2005

A monoclonal antibody (LA‐1) to an adipocyte‐specific plasma membrane protein (64 kD) was used to examine the differential expression of this protein in genetically lean and genetically obese pigs. Enzyme‐linked immunosorbent assay (ELISA) implied the differential expression of the 64 kD protein in adipocyte plasma membranes having different genetic background. Sodium dodecyl‐sulfate polyacrylamide gel electrophoresis (SDS‐PAGE) of genetically lean, genetically obese, and contemporary subcutaneous adipocyte plasma membranes did not indicate any obvious qualitative differences in protein composition. Corresponding immunoblots utilizing LA‐1 confirmed the presence of the 64 kD protein in contemporary and genetically lean adipocyte plasma membranes but absence in genetically obese adipocyte plasma membranes. LA‐1 labelled intact adipocytes isolated from contemporary and genetically lean adipose tissue but did not react with isolated genetically obese adipocytes. The ability to bind to intact adipocytes indicates that the protein is exposed to the extracellular environment. The migration pattern of the protein was not affected by enzymatic deglycosylation by endoglycosidase‐F suggesting that the protein is not highly, if at all, glycosylated. Presence of the 64 kD protein in genetically lean but not genetically obese adipocyte plasma membranes indicates the identification of a novel adipocyte‐specific surface protein associated, either directly or secondary to the onset of obesity, with genetic predispositions for either genetically lean or obese body types in swine.
Multiple types of mRNA‐cytoskeleton interactions
Authors: Zambetti G. , Fey E. G. , Penman S. , Stein J. , Stein G.
Published: May 2005

Nearly all actively translated mRNAs are associated with the cytoskeleton in HeLa cells and the nature of this association is poorly understood. To gain insight into this association, we have examined and compared the cytoskeleton‐mRNA interactions of a signal peptide‐histone fusion mRNA (membrane‐bound polysomal mRNA) to those of endogenous histone mRNA (nonmembrane‐bound polysomal mRNA). We report here the detection of a cytoskeleton attachment site within the signal peptide‐histone fusion mRNP/mRNA nucleotide sequence that is not present in wild‐type histone mRNA or in HLA‐B7 and chorionic gonadotropin‐α membrane‐bound polysomal mRNAs. These results support the possibility that there are multiple mechanisms for the attachment of specific classes of mRNAs to the cytoskeleton.
Characterization of anti‐sticking factor‐II from goat epididymal plasma
Authors: Roy Nabina , Majumder Gopal C.
Published: May 2005

A previous study has characterized the major 47 kDa anti‐sticking factor (ASF‐I) from goat cauda‐epididymal plasma (Roy, N., and Majumder, G. C., Biochim. Biophys. Acta, 991: 114–122, 1989). This study reports the purification and characterization of ASF‐II, another anti‐sticking factor from the goat epididymal plasma. ASF‐II was purified to apparent homogeneity by using concanavalin A–agarose affinity chromatography, DEAE‐cellulose chromatography, alumina gel adsorption, and isoelectric focussing techniques. It showed a single protein band by both non‐denaturing and SDS–polyacrylamide gel electrophoresis. ASF‐II showed a molecular weight of 36,000 and a sedimentation constant of 2.4S. ASF‐II is largely stable to heat treatment and it is a specific glycoprotein having high affinity and specificity for its anti‐sticking action. At saturating concentration (1 nM) it inhibited adhesion of nearly 50% of spermatozoa to the glass surface of the haemocytometer counting chamber. Both the protein and sugar parts of the factor are essential for the anti‐sticking activity since it lost its activity completely when treated with trypsin, L‐fucosidase, or mannosidase. ASF‐II does not coat the glass surface and it binds to spermatozoa. Data are consistent with the view that ASF‐II has not been derived from the larger ASF‐I molecule due to its enzymic modifications. Both ASF‐I and ‐II had no effect on sperm forward motility as evidenced by spectrophotometric motility assays, indicating thereby the suitability of the factors to improve the existing sperm motility assays by eliminating the possibility of cell‐sticking artifacts.
Suppression of tumor cell susceptibility to monocyte‐induced cell death by growth‐inhibitory signals generated during monocyte/tumor cell interaction
Authors: Horn Daniel , van der Bosch Jürgen , Rüller Stephan , Schlaak Max
Published: May 2005

In a recently established serum‐free in vitro system it has been demonstrated that the susceptibility of various human tumor cells to the induction of cell death by elutriated human monocytes is critically dependent on tumor cell density and growth state. In the present work it is shown by flow cytofluorometric analysis of bromodeoxyuridine incorporation rates and of expression of the proliferation‐associated nuclear antigen Ki‐67, that tumor cells forced out of the cell cycle into the quiescent state (G0), which can be accomplished by treatment with supernatant from monocyte/tumor cell interaction cultures, are no longer susceptible to the induction of cell death by monocytes. This suggests that processes essential for the lytic pathway cannot take place in quiescent cells. It is furthermore demonstrated that tumor cells are driven into G0 during interaction with monocytes and that the rate of transit from G1 to G0 increases with increasing monocyte dosage. This explains our earlier finding that maximum rates of tumor cell death are induced at rather low monocyte:tumor cell ratios of around 1:2 and that lysis is suppressed at higher monocyte dosages (van der Bosch et al.: Exp Cell Res 187:185–192, 1990). The potential significance of these findings for the supposed function of mononuclear phagocytes in tumor defense lies in the notion that tumor cells driven into G0 might escape this control and that signals involved in monocyte/tumor cell‐interaction contribute to the accumulation of tumor cells in G0.
Cellular replacement therapy for neurologic disorders: potential of genetically engineered cells
Authors: Chen Lan S. , Ray Jasodhara , Fisher Lisa J. , Kawaja Michael D. , Schinstine Malcolm , Kang Un Jung , Gage Fred H.
Published: May 2005

Neural transplantation, a mode of cellular replacement, has been used as a therapeutic trial for Parkinson's disease. Studies indicate that tonic release of the metabolites from the graft that can be utilized by the host brain, is likely to be the major mechanism responsible for the therapeutic effect. The use of fetal tissue is complicated by ethical controversy and immunological incompatibility. Autografting adult tissue has not been successful mainly due to poor survival. Genetically engineered cells are promising alternative sources of donor cells. We have investigated the potential of primary skin fibroblasts as donor cells for intracerebral grafting. Primary skin fibroblasts survive in the brain and remain in situ. A number of genes (nerve growth factor, tyrosine hydroxylase, glutamic acid decarboxylase, and choline acetyltransferase) have been successfully introduced and expressed in the primary fibroblasts. The L‐dopasecreting primary fibroblasts exhibited a behavioral effect in a rat model of Parkinson's disease up to 8 weeks after being grafted into denervated striatum. Factors that can maximize gene transfer, transgene expression, and fibroblast survival in the brain make up the future direction of investigation.
Brain grafts and Parkinson's disease
Authors: Freed William J. , Poltorak Maciej , Takashima Hidetoshi , Lamarca Mary E. , Ginns Edward I.
Published: May 2005

In animal models, grafts derived from several different tissues, principally fetal substantia nigra and adrenal medulla from young adults, have been found to be effective in alleviating some of the manifestations of lesions of the substantia nigra. It has been suggested that these grafts function by diffusely secreting dopamine, by exerting trophic effects on the host brain, or by producing a new innervation of the host corpus striatum. Evidence for each of these modes of action is briefly reviewed. Several brain tissue transplantation techniques have been described. Each of these techniques has significant limitations in animal models. The significance of these limitations for human application is described, and possibilities for improving the efficacy of brain tissue transplantation in animal models and for human application are discussed.
Applications of immortalized cells in basic and clinical neurology
Authors: Geller Herbert M. , Quiñ;ones‐Jenab Vanya , Poltorak Maciej , Freed William J.
Published: May 2005

Immortalized cell lines can serve as model systems for studies of neuronal development and restoration of function in models of neurological disease. Cell lines which result from spontaneous or experimentally‐induced tumors have been used for these purposes. More recently, the techniques of genetic engineering have resulted in the production of cell lines with specific desired characteristics. This has been accomplished by insertion of a desired gene into a pre‐existing immortal cell or by immortalizing primary cells. The production of immortal cell lines using temperature‐sensitive immortalizing genes offers an additional method of controlling gene expression, and thereby controlling cell proliferation and differentation. In the nervous system, these techniques have produced immortal cell lines with neuronal and glial properties.
Cytoplasmic proteins of porcine adipocytes: identification with monoclonal antibodies
Authors: Wright J. T. , Hausman G. J.
Published: May 2005

In the present study, monoclonal antibodies were produced using porcine adipocyte extracts as the immunogen. Two of the monoclonal antibodies, designated CB6 and IB4, exhibited reactivity toward only cells containing lipid in stromal‐vascular cell cultures. The antigens recognized by the CB6 and IB4 monoclonal antibodies were 50 kD and 55 kD proteins, respectively. In vivo, IB4 immunoreactivity was detected only in lipid‐containing cells, whereas immunofluorescence using CB6 was also detectable around muscle fiber bundles underlying the subcutaneous mesenchyme. In fetal subcutaneous mesenchyme, CB6 and IB4 immunoreactivities toward lipid‐containing cells increased with developmental age, but each was not detectable in cells containing the smallest lipid droplets. In stromal‐vascular cultures containing adipocytes, 48 hour treatment with the anti‐lipogenic agent, growth hormone, only slightly altered CB6 immunoreactivity, whereas IB4 immunoreactivity was reduced by more than sixfold. The exact identity of the CB6 and IB4 antigens was not determined, but each may be useful as markers for studying regulation of adipocyte metabolism.
Isolation of heparan sulfate proteoglycan from beneath the monolayers of rat hepatocytes and its binding to type IV collagen
Authors: Babu P. B. Santhosh , Sudhakaran P. R.
Published: May 2005

Primary cultures of rat hepatocytes maintained as monolayer in a serum‐free medium synthesise and secrete sulphated proteoglycans. Nearly 5% of the total 35(S)‐sulphated material was obtained in a soluble form from beneath the cell layer. A shift in gel filtration pattern on β‐elimination with alkali suggested that it is a sulphated proteoglycan. On ion exchange chromatography over Dowex AG 1×2, the major fraction was eluted with 1.25 M NaCl. Further, nearly 80% of the 35(S)‐labeled material was susceptible to nitrous acid degradation and more than 90% of the material was resistant to chondroitinase ABC digestion suggesting that it is predominantly a heparan sulphate proteoglycan (HSPG). Since HSPG is a major component of basement membrane, its binding with collagen was studied by a solid phase binding assay. About 75% of the 35(S) HSPG bound to wells coated with type IV collagen whereas only about 20% bound to type I collagen at physiological pH. Binding to collagen IV was reduced by about 50% when free GAG chains were used indicating that the protein core is also involved in interaction with the collagen. These results indicate the possible role of this basal extracellular heparan sulphate proteoglycan in the basal lamina formation.