On the heterogeneity of native ribosomal subunits in Ehrlich-ascites-tumor cells cultured in vitro

Native small ribosomal subunits in cultured Ehrlich ascites tumor cells, analyzed by high-resolution CsCl isopycnic centrifugation, consist of at least five classes of particles. These particles with buoyant densities of 1.39, 1.42, 1.45, and 1.51 g/cm3 were designated as SI, SII, SIII, SIV and SV, respectively. They were different from the ribosome-derived 40-S subunits which have a density of 1.54 g/cm3. Native large ribosomal subunits consist of at least two classes of particles with densities of 1.57 g/cm3 (LI) and 1.59 g/cm3 (LII), respectively. The ribosome-derived 60-S subunits have the same buoyant density as LII particles. Labeling of Ehrlich ascites cells with radioactive uridine and a subsequent chase in the presence of RNA-synthesis inhibitors shows that radioactivity was incorporated first in precursor particles with a density of 1.48 g/cm3 and then subsequently appeared in SIII and SII particles. Met-tRNAf is found exclusively on native 40-S particles with densities of 1.42 and 1.49 g/cm3. This result has been observed in cells labeled with [35S] methionine in vivo as well as with tRNA charged in vitro. The possibility that SII particles contain 40-S initiation complexes is discussed.     

Effect of keratinocyte seeding of collagen-glycosaminoglycan membranes on the regeneration of skin in a porcine model

A collagen-glycosaminoglycan matrix, impregnated with autologous keratinocytes, was applied as island grafts onto full-thickness porcine wounds to determine whether complete epidermal coverage could be achieved in a single grafting procedure. Twenty-four grafts with seeding densities ranging from 0 to 3,000,000 cells/cm2 were used to determine the kinetics of epidermal coverage. The time sequence of epidermal formation was then studied between days 14 and 28 using four additional grafts, each seeded with a density of 500,000 cells/cm2. Autologous keratinocytes proliferated as the collagen-glycosaminoglycan matrix was vascularized to form a confluent epidermis by 2 weeks in matrices seeded with at least 100,000 cells/cm2. The epidermal thickness and the number of keratinocyte cysts observed in the neodermis at 2 weeks increased linearly with the logarithm of the seeding density. Sequential analysis of neoepidermis showed the nascent epidermis to be hyperplastic, parakeratotic, and focally lacking in granular layer differentiation at 2 weeks. After 2 weeks, it underwent normal maturation and differentiation. Irrespective of seeding density at 2 weeks the collagen-glycosaminoglycan matrix was well vascularized, contained a dense cellular infiltrate, and was almost completely degraded. These studies demonstrate that seeded keratinocytes proliferate and differentiate to form a confluent epidermis by 2 weeks in matrices seeded with at least 100,000 cells/cm2.     

The in vivo effects of 2.45 GHz microwave radiation of rabbit serum components and sleeping times

An investigation was conducted to determine the effects of relatively low power density microwave exposures on various serum components of the Dutch rabbit. Both continous wave and pulsed mode exposures at 2.45 GHzwere used at power densities of 25,10 and 5 mW/cm2. Studies of 10 serum components were performed. Additional studies were conducted on changes in sleeping times of pentobarbital-sedated rabbits at various power densities. Gross and histopathological examinations were performed on representative samples of animals. Changes in the blood chemistry of irradiated animals were consistent with a dose-dependent response to a non-specific thermal stress at all power densities used. Observed physiological response, as well as rectal temperature measurements, indicated that the thermoregulatory capability of the rabbits was sufficient to compensate for the thermal burden at 5 and 10 mW/cm2, but could be overridden by a 2 h exposure at 25 mW/cm2. Pathology findings included a mild, repairable nephrosis in animals exposed at a power density of 25 mW/cm2. A further investigation of analeptic effects at power densities varying from 5 mW/cm2 to 50 mW/cm2 resulted in a statistically significant decrease in sleeping times, apparently proportional to power density below 15 mW/cm2.     

Ice/ced-3 family gene and apoptosis

Apoptosis is a process by which cells carry out their own execution by activating an orderly set of genetic and biochemical program. A genetic pathway of apoptosis has been identified in the nematode Caenorhabditis elegans. The ced-3 gene is required for all programmed cell death in C. elegans. Mammalian homolog of ced-3 has been identified as Ice family which is newly identified cysteine protease. Overexpression of Ice/ced-3 family gene can induce apoptosis in a variety of mammalian cells, and inhibitors of Ice/ced-3 family effectively prevent apoptosis induced by a variety of stimulus. Several housekeeping genes have been shown to be targets of Ice/ced-3 family gene, indicating that activation of Ice/ced-3 can induce irreversible fatal changes of cells.     

Childbearing, reproductive control, aging women, and health care: the projected ethical debates

We have examined the effects of an integrin-binding competitor, echistatin, in solution on adhesion and migration of rat microvessel endothelial cells on fibronectin in vitro. A biphasic dependence of cell motility on fibronectin surface density was observed, with a peak random motility coefficient of about 8 x 10(-9) cm2/sec occurring below 0.3 microgram/cm2 fibronectin. In the presence of echistatin at 0.5 microM, the peak random motility coefficient was similar but occurred at the significantly greater fibronectin surface density of 1.2 micrograms/cm2. Hence, the same concentration of this soluble integrin-binding competitor inhibited migration on low fibronectin densities but enhanced migration on high fibronectin densities. At the same time, echistatin decreased adhesiveness on all fibronectin surface densities. When motility was correlated explicitly with adhesiveness, a single biphasic relationship was obtained for both absence and presence of echistatin with peak motility occurring in both cases at identical adhesiveness. Both the inhibiting and enhancing effects of the soluble integrin-binding competitor on motility are predictable from its effect on adhesion, consistent with the theoretical models of Lauffenburger (15) and DiMilla et al. (3).     

Thin film rechargeable lithium batteries for implantable devices

Thin films of LiCoO2 have been synthesized in which the strongest x-ray reflection is either weak or missing, indicating a high degree of preferred orientation. Thin film solid state batteries with these textured cathode films can deliver practical capacities at high current densities. For example, for one of the cells, 70% of the maximum capacity between 4.2 and 3 V (approximately 0.2 mAh/cm2) was delivered at a current of 2 mA/cm2. When cycled at rates of 0.1 mA/cm2, the capacity loss was < or = 0.001%/cycle. The reliability and performance of Li-LiCoO2 thin film batteries make them attractive for application in implantable devices such as neural stimulators, pacemakers, and defibrillators.     

Laser-induced photoacoustic effects in the dentin]

To study photoacoustic effects in dentin caused by UV-laser ablation, laser-induced shockwaves were measured using piezoelectric PVDF films. Above the tissue-specific energy threshold for photoablation the amplitude of the acoustic shock waves is proportional to the applied laser energy density. Laser energy densities of 2 J/cm2 cause pressure amplitudes of 50 bar, densities of 20 J/cm2 cause pressure amplitudes of 1000 bar. To avoid microcracks in dentine the maximum laser energy density to prepare dentin should be limited to approximately 20 J/cm2.     

Electroremediation of Naphthalene in Aqueous Solution Using Alternating and Direct Currents

The key objectives of this study were to evaluate the use of an alternating current (AC) for the degradation of naphthalene in spiked aqueous solutions and to investigate the effect of current density on the degradation rates of naphthalene. Direct current (DC) was also used to compare the rates of degradation. Sodium chloride (NaCl) and anhydrous sodium sulfate (Na2SO4) were used as the supporting electrolytes. Degradation rates and byproducts formed were investigated when DC and AC were separately passed through naphthalene solutions. A square wave AC, having a frequency equal to 0.1?Hz was used. Naphthalene solutions having an initial concentration of about 20?mg/L ( ～ 0.15?mM) were subjected to an AC peak current density and DC density of 6?mA/cm2, using NaCl as the supporting electrolyte. An approximate 65% reduction in the concentration of naphthalene was observed after a period of 48 h when DC was applied. Degradation was almost 100% when the AC was applied during the 48-h period. The effect of current density on the electrochemical degradation rate of naphthalene in aqueous solution was also investigated at alternating and direct current densities of 1, 3, and 6?mA/cm2 using Na2SO4 as the supporting electrolyte. AC peak current densities of 1, 3, and 6?mA/cm2 resulted in overall conversions of 77, 87, and 95%, respectively, of naphthalene in solution. The corresponding values for DC application were 95% for all current densities while the initial degradation rates were greater at higher DC densities. Based on the degradation products formed, hydroxylation is believed to be the key mechanism for the degradation of naphthalene.     

Electrochemical Preparation of La—Fe Alloy Films in Dimethylsulfoxide（DMSO）

Ｒａｒｅｅａｒｔｈｓａｎｄｔｈｅｉｒａｌｌｏｙｓｈａｖｅｓｐｅｃｉｆｉｃｐｒｏｐｅｒｔｉｅｓ ,ｓｕｃｈａｓｍａｇｎｅｔｉｃ ,ｏｐｔｉｃａｌ,ｅｌｅｃｔｒｉｃａｎｄｈｙｄｒｏｇｅｎｓｔｏｒａｇｅ .Ｔｈｅｙｈａｖｅｂｅｅｎｗｉｄｅｌｙａｐｐｌｉｅｄｔｏｖａｒｉｏｕｓｆｕｎｃｔｉｏｎａｌｍａｔｅｒｉａｌｓ .ＴｈｅＬａ Ｆｅａｌｌｏｙｓｈａｖｅｂｅｅｎａｐｐｌｉｅｄａｓｍａｇｎｅｔｉｃｍａｔｅｒｉａｌｓ .Ｓｉｎｃｅｒａｒｅｅａｒｔｈｅｌｅｍｅｎｔｓａｒｅｖｅｒｙａｃｔｉｖｅ,ｉｔｉｓｖｅｒｙｄｉｆｆｉｃｕ…     

Combined enzyme histochemical and ultrastructural study on cryostat sections of pig heart to detect early reperfusion damage after ischaemia

In cardiac surgery, recognition of peroperative myocardial infarction may improve patient selection for prolonged circulatory support. The value of enzyme histochemistry to discriminate between reversible and irreversible myocardial damage at short periods of reperfusion was studied in an in vivo model of regional ischaemia in pig hearts. The left anterior descending coronary artery (LADCA) was clamped for 45 min followed by 2 h reperfusion (group 1, n = 3). Post-mortem heart tissue showed markedly decreased activities of lactate dehydrogenase (LDH) and beta-hydroxybutyrate dehydrogenase (BDH) as demonstrated in cryostat sections, accompanied by massive leakage of LDH in the venous effluent. The depleted areas showed irreversible cell damage based on the presence of flocculent densities in mitochondria. In group 2 (n = 6), LADCA flow was reduced to 40 per cent of the base-line value followed by 2 h reperfusion. Heart tissue showed normal LDH and BDH activities, except for some cells surrounding blood vessels, which activity was minimally decreased. Flocculent densities in mitochondria were never observed. We conclude that enzyme histochemistry of LDH and BDH activity on cryostat sections is a useful tool for detecting irreversible myocardial cell damage as early as 2 h reperfusion after ischaemia of the pig heart. The technique has potential applications in the detection of peroperative infarction in human biopsies.     

The effect of intracellular protease inhibitors on DNA synthesis in fibroblasts from the NIH 3T3 mouse strain

The enhancement of catabolic reactions of cell macromolecules, primarily proteins, raises the question about the role of active proteolysis and particular kinds of proteases in the process leading to cell proliferation retardation. The application of highly specific inhibitors of intracellular proteases helps to answer this question even in part. It has been shown that a short-term (2-6 h) treatment of resting cells of line NIH 3T3 with inhibitors of lysosomal cysteinous proteases--cystatine or leupeptin, as well as with inhibitors of non-lysosomal Ca(2+)-activated cystein proteases--L-cystamine and L-cystin--enhances the cell proliferative response on the serum and even stimulates tritiated thymidine incorporation in the cells cultured in the medium with a low (0.2%) serum content. Unlike, the treatment of resting cells with the lysosomotropic agent chloroquin, known to shut down all lysosomal hydrolases, reduces the cell proliferative response of the serum. In the experiments of fusing the resting and stimulated cells, it was found that the pretreatment of the former with inhibitors of lysosomal proteases enhanced the index of labeled nuclei in the latter, while observed in dikaryons, compared to the control, although failed to remove totally the effect of DNA synthesis inhibition in heterokaryons (Setkov et al., 1984; Setkov, Kazakov, 1989). A conclusion is made that the short-term metabolic shift in resting cells towards anabolism may result in that resting cells commit a cycle, and that an enhanced activity of cystein proteases is one of specific metabolic processes in resting cells leading to proliferation retardation.     

Determining energy density distribution in laser irradiation fields, generated by the LILAB system

Laser energy densities of less than 1 J/cm2 had no apparent effect on human tissues, while energy densities of more than 4 J/cm2 resulted in tissue damage. For non-punctiform laser applications, therefore, a laser beam distribution system that provides a homogeneous energy density distribution is of advantage, since such a system permits safe application of the laser in the effective therapeutic range. Conventional laser scanners for medical use have been reported to produce grossly inhomogeneous energy density distributions. The new LILAB system, which is a very fast laser beam distribution system, readily generates application fields of different configuration with high homogeneous energy density distribution. The article presents an example of a randomly selected application field, in which the energy densities at the edges and at the centre are compared.     

An ultrastructural study of heterokaryons derived from Theileria parva-infected bovine lymphoblasts and Ehrlich ascites tumour cells

An ultrastructural study was made of Sendai virus induced heterokaryons derived from Theileria parva-infected lymphoblasts and Ehrlich ascites tumour cells. When fusion occurred, parasites were successfully integrated into the cytoplasm of the resulting heterokaryons where they appeared as morphologically normal macroschizonts. Homokaryon formation was also noted. This occurred frequently between Ehrlich ascites tumour cells and rarely with lymphoblasts. A small proportion of heterokaryons contained altered forms of T parva showing nuclear components, vesicular structures and paired organelles similar to the microshizont stage of the parasite.     

The effect of leukotriene D4 on the patency of nasal passage in the guinea pig

BACKGROUND: Demodex folliculorum has been reported in rosacea in a number of clinical studies. As the Demodex mite is also present in many healthy individuals, it has been suggested that the mite may have a pathogenic role only when it is present in high densities. Moreover, some authors have proposed that a mite density above 5/cm2 may be a criterion for the diagnosis of inflammatory rosacea. In this study, the possible role of D. folliculorum and the importance of mite density in rosacea were investigated using a skin surface biopsy technique. METHODS: Thirty-eight patients with rosacea and 38 age-and-sex-matched healthy subjects entered the study. With the skin surface biopsy technique, we obtained samples from three facial sites. We then determined the mite positivities, the mean mite counts in both study groups, the mean mite densities at each facial site and in the rosacea subgroups, and the mite densities above 5/cm2. RESULTS: The mean mite count in the rosacea group (6,684) was significantly higher than that in controls (2,868; p < 0.05). The cheek was the most frequently and heavily infested facial region. Ten rosacea patients and five normal subjects had mite densities over 5/cm2; the difference was not statistically significant (p > 0.05). CONCLUSIONS: Rosacea is a disease of multifactorial origin, and individual properties may modify the severity of the inflammatory response to Demodex. We suggest that a certain mite density is not an appropriate criterion in the diagnosis of the disease; nevertheless, large numbers of D. folliculorum may have an important role in the pathogenesis of rosacea, together with other triggering factors.     

Mg-Al-Pb-Ga-Y海水电池用镁阳极的 成分优化和电化学性能

采用熔炼法制备了一系列Mg-Al-Pb-Ga-0.9Y海水电池用镁合金阳极材料.利用金相显微镜（OM）、扫描电镜（SEM）、X射线衍射（XRD）和电化学测试等方法研究了Pb、Ga元素对合金组织和电化学性能的影响.结果表明, 合金的放电电压随Pb含量增加而提高. Pb含量（指质量分数，下同）为5%且Ga的添加量为1%时, 对放电电压的提升效果达到最优，合金在20 mA/cm2和100 mA/cm2电流密度下放电均有较大的放电电压.成分为Mg-3Al-5Pb-1Ga-0.9Y的镁阳极具有更优异的综合性能, 其放电电位最负, 在电流密度为20 mA/cm2和100 mA/cm2下的工作电位分别为-1.723 V和-1.680 V；合金的自腐蚀速率较低, 腐蚀电流密度为5.1164×10-5 A/cm2.      

The nature of copper electrowon in the presence of iron using sulfur dioxide sparging

The nature of copper electrodeposits obtained under conditions of ferrous oxidation and gas (SO₂ with N₂/air) sparging has been studied using synthetic solutions in the absence of organic inhibitors. The quality of the deposit was improved by increasing the sparging rate and temperature and by decreasing the applied current density and sulfuric acid concentration. The copper deposits were found to contain about 14 μg/g sulfur compared with 5 μg/g in the starter cathode. The texture of the deposits was affected by the rate of gas sparging and applied current density. A pyramidal morphology was observed at current densities in the order of 200 A/m². At higher current densities polycrystalline, unoriented dispersion-type deposits were obtained.     

Behavioral thermoregulation in the squirrel monkey: Adaptation processes during prolonged microwave exposure.

Investigated exposure duration at power densities above and below the threshold of 6-8 mW/cm2 with 2 male monkeys. Ss were restrained in the far field of a horn antenna inside an anechoic chamber heated and cooled by forced convection. Ss learned to control the temperature of the circulating chamber air by selecting between cold and warm air sources. Ss were exposed to 12.4-cm (2450-MHz) continuous-wave microwaves for periods from 5 to 150 min. Microwave power densities explored were 4, 10, and 20 mW/cm2. The 4 mW/cm2 microwave exposure did not modify thermoregulatory behavior. The 10 and 20 mW/cm2 exposures stimulated the monkeys to select ambient temperatures 1.5 and 3.0°C cooler than control levels, respectively. Except during the early minutes of an exposure, duration had no significant effect on selection of air temperature or on the body temperatures thereby achieved. (25 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

KCl-NaCl-NaF-SiO_2熔盐体系中硅离子的还原机理研究

在KCl-NaCl-NaF-SiO2熔盐体系中,以铂丝为参比电极、研究电极,高纯石墨坩埚为辅助电极,采用循环伏安法和计时电位法对硅离子的还原机理进行了研究,结果表明此电化学反应为扩散控制的不可逆电极过程;求得硅离子在熔盐中的扩散系数D=1.33×10-3cm2/s(CSi4+=1.21×10-4mol/cm3,T=1 073 K)。     

Wild-type p53 triggers a rapid senescence program in human tumor cells lacking functional p53

The p53 tumor suppressor gene has been shown to play an important role in determining cell fate. Overexpression of wild-type p53 in tumor cells has been shown to lead to growth arrest or apoptosis. Previous studies in fibroblasts have provided indirect evidence for a link between p53 and senescence. Here we show, using an inducible p53 expression system, that wild-type p53 overexpression in EJ bladder carcinoma cells, which have lost functional p53, triggers the rapid onset of G1 and G2/M growth arrest associated with p21 up-regulation and repression of mitotic cyclins (cyclin A and B) and cdc2. Growth arrest in response to p53 induction became irreversible within 48-72 h, with cells exhibiting morphological features as well as specific biochemical and ultrastructural markers of the senescent phenotype. These findings provide direct evidence that p53 overexpression can activate the rapid onset of senescence in tumor cells.     

Protein structure-based design, synthesis, and biological evaluation of 5-thia-2,6-diamino-4(3H)-oxopyrimidines: potent inhibitors of glycinamide ribonucleotide transformylase with potent cell growth inhibition

The design, synthesis, biochemical, and biological evaluation of a novel series of 5-thia-2,6-diamino-4(3H)-oxopyrimidine inhibitors of glycinamide ribonucleotide transformylase (GART) are described. The compounds were designed using the X-ray crystal structure of human GART. The monocyclic 5-thiapyrimidinones were synthesized by coupling an alkyl thiol with 5-bromo-2, 6-diamino-4(3H)-pyrimidinone, 20. The bicyclic compounds were prepared in both racemic and diastereomerically pure forms using two distinct synthetic routes. The compounds were found to have human GART KiS ranging from 30 microM to 2 nM. The compounds inhibited the growth of both L1210 and CCRF-CEM cells in culture with potencies down to the low nanomolar range and were found to be selective for the de novo purine biosynthesis pathway. The most potent inhibitors had 2,5-disubstituted thiophene rings attached to the glutamate moiety. Placement of a methyl substituent at the 4-position of the thiophene ring to give compounds 10, 18, and 19 resulted in inhibitors with significantly decreased mFBP affinity.