Effect of silica on phospholipase D activity in rat alveolar macrophages

Silica may act as a stimulator of pulmonary inflammation and fibrosis. The effect of silica on phospholipase D (PLD) activity assayed as accumulation of [3H]phosphatidylethanol ([3H]PtdEt) was examined in [3H]palmitic acid-labeled primary cultures of rat alveolar macrophages. Silica induced a rapid accumulation of [3H]PtdEt in a time (0, 15, 30 and 45 min)- and concentration (0.5, 1.0, 2.5 and 5.0 mg/ml)-dependent manner indicating PLD activation. This silica-stimulated PLD activity was attenuated by the pretreatment with calcium chelator ethylene glycol-bis(beta-aminoethyl ether) N,N,N',N'-tetraacetic acid (EGTA) or/and 1,2-bis(2-aminophenoxy)ethane-N,N,N,N-tetraacetic acid acetoxymethyl ester (BAPTA/AM) (EGTA: 54.3 +/- 8.6%, BAPTA/AM: 67.5 +/- 7.8% and EGTA + BAPTA/AM: 35.8 +/- 2.9, respectively). Also, silica-induced PLD activation was partially inhibited by the pretreatment with nonspecific phospholipase C (PLC) and PLD inhibitor (neomycin; 66.4 +/- 4.8%) or specific PLC inhibitor (U73122; 70.8 +/- 4.6%). Sphingosine as a protein kinase C (PKC) inhibitor did not change silica-induced PLD activity indicating that PKC might not play a role in PLD activation by silica. Based on these results, we concluded that a silica-stimulated phospholipase D activity is present in the rat alveolar macrophages and is predominantly regulated by PLC-mediated intracellular calcium.

Upregulation of urokinase in alveolar macrophages and lung tissue in response to silica particles

Impaired fibrinolytic activity and persistent fibrin deposits in lung tissue have been associated with lung fibrotic disorders. The present study examined the sources of plaminogen activator (PA) changes induced by a single intratracheal administration of silica particles (5 mg) in the mouse lung. We found in both control and silica-treated animals that amiloride almost totally abolished PA activity in bronchoalveolar lavage (BAL) fluid (BALF), indicating that initial upregulation (from day 1) as well as sustained PA activity (up to day 30) observed in response to silica is related to changes in urokinase-type PA (uPA). The upregulation of BALF uPA activity was associated with a marked and persistent increase in uPA mRNA levels in lung tissue. Changes in uPA expression were also reflected in the BAL cell fraction. A maximal and constant increase in cell uPA activity was associated with the early response to silica, whereas significant but lower upregulation was still noted at the fibrotic stage. From days 3 to 30, a progressive increase in uPA mRNA levels was noted in BAL inflammatory cells elicited by silica. Because the number of BAL neutrophils was strongly correlated with BALF and BAL cell-associated uPA activity, their involvement in uPA upregulation was addressed by inducing neutropenia with cyclophosphamide (200 mg/kg ip) before administration of the silica. Neutrophilic depletion did not, however, reduce, and even increased, the BAL cell-associated uPA activity. At the BALF level, neutropenia did not change PA activity in silica-treated mice, pointing to alveolar macrophages as the principal source of uPA in response to silica. Immunohistochemical stainings identified alveolar macrophages and pneumocytes as uPA-expressing cells in silica-treated animals (day 30). Intense and heterogenous staining was observed in silicotic nodules. These findings indicate that urokinase produced by alveolar macrophages is operative not only at the alveolitis stage but also later in the fibrotic process, produced by silica particles, supporting the role of uPA in fibrogenesis.

Effects of silica exposure on substance P immunoreactivity and preprotachykinin mRNA expression in trigeminal sensory neurons in Fischer 344 rats

Trigeminal sensory neurons innervate the nasal cavity and may release substance P (SP) upon exposure to inhaled irritants. The purpose of this study was to determine if silica dust, an occupational irritant causing inflammation, activates sensory neurons supplying the nasal cavity. Male Fischer 344 rats were placed in inhalation chambers and exposed daily to 2 mg/m3 of fresh silica (average diameter 1 microm) for 6 mo. Following exposure, the trigeminal ganglia (TG) were removed and prepared for SP immunocytochemistry and for preprotachykinin (PPT) autoradiographic in situ hybridization. The SP-like immunofluorescence in TG neurons was subjectively categorized as high, moderate, or low (background) intensity. In situ hybridization autoradiographs were quantified on the basis of grain density using digital imaging analysis. The SP immunoreactivity and PPT mRNA expression in the TG neurons were significantly increased after silica inhalation. The proportion of highly positive SP-immunoreactive neurons shifted from 1.30 +/- 0.58% in controls to 11.30 +/- 1.15% after silica treatment. The neurons exhibiting high grain density for PPT mRNA increased from 1.50 +/- 0.87% in controls to 11.67 +/- 0.58% in the silica group. Thus, inhalation of silica causes upper airway irritation resulting in increased levels of immunoreactive neuronal SP and PPT mRNA. These findings suggest that silica activates sensory pathways that may be involved in nasal inflammation.

Shedding of CD44 from PMA-differentiated U-937 cells is enhanced by treatment with mineral particles

In this report, we show that enhanced shedding of CD44 might contribute to the down-regulation of this receptor observed after phagocytosis of MnO2 particles by PMA-differentiated U-937. The apparent Mr of the soluble CD44 detected in culture supernatants was slightly lower than that of the membrane form suggesting that shedding resulted from proteolytic cleavage. Increased shedding of CD44 was also noted with other mineral particles (chrysotile and DQ12) but to a lower extent whereas some (TiO2 and amosite) had no effect on this process. These results indicate that shedding enhancement was particle-specific rather than a general consequence of phagocytosis. The ability of the particles to enhance CD44 shedding was not directly dependent on their cytotoxic potency. Different patterns of reactivity were noted with CD11b, suggesting that the underlying mechanisms are specific.

The effect of various storage methods and media on shear-bond strengths of dental composite resin to bovine dentine

A variety of media and methods have been used to store teeth used in bond-strength studies of resin restorative materials to dentine. This study examined the effect of 2 months of storage using 11 different methods and media on the shear-bond strength of Z100 resin composite to bovine dentine mediated by Scotchbond Multi Purpose adhesive. Freshly harvested teeth were used as controls. The results showed that 7 of the l1 storage methods or media were similar in shear-bond strengths and bond-failure characteristics. Four of the 11 methods (irradiation, or storage in thymol, methanol, and glutaraldehyde) resulted in significantly lower shear-bond strengths and atypical shear-bond failure, indicating that these are the least desirable methods of tooth storage for studies of this type. This study has further shown that if insufficient numbers of fresh teeth are available for studies of shear-bond strength, then freezing is the preferred method of storage for the registration of high shear-bond strengths. It is also apparent that further investigations are needed to examine what post mortem changes occur in dentine, whether these changes are modified by various storage conditions, and whether they have any significant effect on bonding of resin composites.

Role of urokinase in the fibrogenic response of the lung to mineral particles

The lung plasminogen activator (PA) response was examined in four different models of particle-induced pulmonary lesions in NMRI mice (single intratracheal administration, 0.75 to 5 mg/mouse). Sequential changes in cellular (total and differential counts) and biochemical markers of alveolitis (lactate dehydrogenase [LDH], total proteins) were monitored in bronchoalveolar fluid (BALF) and the fibrotic lung response was assessed histologically. An intense but spontaneously resolving alveolitis was produced by manganese dioxide (MnO2) and a fibrosing alveolitis was elicited by crystalline silica (DQ12). Minimal and noninflammatory responses were obtained after instillation of titanium dioxide (TiO2) and tungsten carbide (WC), respectively. The comparison between the resolving and the fibrosing alveolitis model was especially taken into consideration in an attempt to identify fibrinolytic changes associated with the development of fibrosis. At the alveolitis stage, similarly increased BALF PA activities were measured in both the resolving and the fibrosing alveolitis models whereas only slight and no PA modifications were noted after administration of TiO2 and WC, respectively. Persistently (up to 120 d) increased BALF PA activity was selectively associated with the progression to fibrosis (DQ12), suggesting that PA is involved in the fibrotic process. ELISA measurements demonstrated that the changes in BALF PA activity were exclusively related to changes in urokinase (uPA), not tissue-type PA. A rapid and persisting (up to Day 30) upregulation of cell-associated PA activity occurred after DQ12, MnO2, and TiO2 treatment only. Cellular PA activity was however significantly higher in fibrogenic inflammatory cells recovered from DQ12 than from MnO2-treated mice suggesting that the intensity of cellular PA upregulation may represent an early indicator of the progression to fibrosis. The implication of urokinase in the pathogenesis of silica-induced fibrosis was demonstrated by the use of a uPA knockout mice. The acceleration of the fibrotic process in uPA-deficient compared with the wild type animals demonstrated the contribution of uPA to limit the fibrotic process.

Spontaneous and follicular fluid-induced acrosome reaction in sperm samples from in vitro fertilizing and nonfertilizing normozoospermic patients

PURPOSE

One of the most challenging and intriguing groups of infertile patients is that of normozoospermic men who have repeatedly not achieved fertilization in vitro. These cases probably present a wide range of gamete disorders manifested at different stages of the fertilization process. The occurrence of spontaneous and follicular fluid (FF)-induced acrosome reactions (ARs) in in vitro fertilizing and nonfertilizing specimens from normozoospermic IVF patients was assessed, and the effect of Percoll and cryopreservation on the incidence of ARs was evaluated.

METHODS

Semen samples from 62 normozoospermic (15 in vitro nonfertilizing and 47 fertilizing) patients were analyzed. Spermatozoa were double-stained with FITC-conjugated Pissum sativum lectin, to assess their acrosomal status, and propidium iodide, to evaluate their vitality, using flow cytometry analysis.

RESULTS

A lower average of AR incidence was observed in the nonfertilizing than in the fertilizing group with all treatments. Both groups exhibited an increase in the proportion of ARs following incubation with FF. This rise was most prominent when Percoll-separated fractions were used (15.8 and 25.6% AR in the nonfertilizing and fertilizing groups, respectively). Thawed cryopreserved and fresh fertilizing samples exhibited similar AR rates.

CONCLUSIONS

That normozoospermic recurrently nonfertilizing compared to fertilizing semen samples have a lower capacity to undergo ARs is suggested.

Role of hydroxyl radical in silica-induced NF-kappa B activation in macrophages

Nuclear transcription factor kappa B (NF-kappa B) is a multiprotein complex that regulates a variety of genes important for immunity and inflammation. The present study investigates the silica-induced activation of this transcription factor in mouse macrophage cell line RAW 264.7 cells, the role of free radical reactions in the mechanism of the activation, and its possible inhibition. Tetrandrine, a benzylisoquinoline alkaloid, which has been used as an antifibrotic drug to treat the lesions of silicosis and has been characterized as a hydroxyl radical (.OH) scavenger, inhibited the NF-kappa B activation induced by silica, lipopolysaccharide (LPS), and phorbol 12-myristate 13-acetate (PMA). Catalase, metal chelator, deferoxamine, and the silanol group (SiOH) blocker, poly(2-vinylpyridine-N-oxide) (PVPNO), also inhibited silica-induced NF-kappa B activation. Electron spin resonance (ESR) spin trapping measurements show that both deferoxamine and PVPNO decreased silica-mediated .OH radical generation from H2O2. It is shown that Fe(II) and not Fe(III) is able to cause NF-kappa B activation. The antioxidant, ascorbate, attenuated the NF-kappa B activation induced by silica but not by LPS. The .OH radical scavenger, sodium formate, inhibited NF-kappa B activation induced by silica but had only a minor effect on NF-kappa B activation induced by LPS. The results indicate that silica-mediated free radical generation via the Fenton or Fenton-like reaction (M(n)+ + H2O2-->M(n + 1)+ + OH- + .OH) and silanol groups on the silica surface play an important role in silica-induced NF-kappa B activation.

Purification and characterization of a silica-induced bronchoalveolar lavage protein with fibroblast growth-promoting activity

Experimentally induced silicosis provides a good model for chronic interstitial pulmonary inflammation and fibrosis. In the present study, a specific single polypeptide with an apparent molecular mass of 58,000 and a pl of 4.5 was purified and characterized from the bronchoalveolar lavage fluid of silicotic rats. The same protein was also isolated from both the extract and conditioned medium of alveolar macrophages of silicotic rats. Therefore, this protein was termed an inducible silicotic (rat) bronchoalveolar lavage protein-p58 (iSBLP58) or an inducible silicotic (rat) pulmonary macrophage factor (iSPMF-p58). iSBLP58 has been purified to homogeneity by a combination of gel permeation, Mono Q ion exchange, and reverse-phase high performance liquid chromatography. This polypeptide displayed a potent fibroblast growth-promoting activity in vitro. The sequence of the first 15 NH2-terminal amino acids was determined and was found to have high sequence homology with members of the mammalian chitinase-like protein family, which includes human cartilage gp39, mammalian oviduct-specific glycoprotein, and a secretory protein from activated mouse macrophages.

Ferritin expression after in vitro exposures of human alveolar macrophages to silica is iron-dependent

The increased availability of catalytically active iron after silica exposure can present an oxidative injury to a living system. Sequestration of reactive iron would, therefore, confer a protective effect. The intracellular storage of iron by ferritin within macrophages can limit the potential for radical generation and cellular injury resulting from exposure to a metal chelate. We tested the hypothesis that in vitro exposure of human alveolar macrophages to silica increases the expression of ferritin through a posttranscriptional mechanism. Exposure of 1.0 x 10(6) macrophages to 100 microg/ml silica for 4 h increased light-subunit (L)-ferritin protein concentrations in both cell supernatants and lysates. Inclusion of 1.0 mM deferoxamine in the reaction mixtures inhibited increases in ferritin after silica. To test for a posttranscriptional regulation of ferritin protein expression, cells were incubated with acid-washed particles, silica with complexed zinc cation, and silica with complexed iron cation. L-ferritin protein concentrations were increased in both cell supernatants and lysates after 4 h of exposure to silica with complexed iron cation. There were no increases in L-ferritin after incubations with acid-washed particles or silica with complexed zinc cation. There were no significant differences in levels of L-ferritin cDNA between any of the exposures, suggesting a posttranscriptional control of ferritin expression.

[Experimental affecting of pulmonary clearance of Pasteurella multocida induced pneumonia in swine]

The pulmonary clearance of Pasteurella multocida in weaner pigs was not affected by Carrageenan and Silica, two substances which block the function of monocytes/macrophages. Neutropenia, caused by the application of hydroxyurea, however, inhibit the pulmonary clearance markedly and reduced the severity of simultaneously induced pneumonias considerably. This indicates the importance of polymorphonuclear neutrophils for early clearance mechanisms and their inflammation inducing and maintaining effects.

Efficacy of taurine based compounds as hydroxyl radical scavengers in silica induced peroxidation

While it is widely believed that taurine may play an important role in protecting cells against toxic injury by functioning as an antioxidant, there is a lack of evidence to support this hypothesis. In this study, electron spin resonance (ESR) was used to investigate the reaction of taurine and hypotaurine with hydroxyl radicals (.OH). The Fenton reaction (Fe(II) + H2O2-->Fe(III) + .OH + OH-) and the Cr(V)-mediated Fenton-like reaction (Cr(V) + H2O2-->Cr(VI) + .OH + OH-) were used as sources of .OH radicals. The results show that hypotaurine but not taurine effectively scavenges .OH radicals with a reaction rate constant of k = 1.6 x 10(10) M-1s-1. That is comparable with other efficient .OH radical scavengers. The effect of taurine and hypotaurine on silica-induced lipid peroxidation was evaluated using linoleic acid as a model lipid. Hypotaurine, but not taurine, caused a significant inhibition of silica-induced lipid peroxidation. The results show that hypotaurine is an excellent antioxidant and appears to have the potential for being a therapeutic agent against silica-induced lung injury.

Early increase in expression of surfactant protein A gene in type II cells from silica-treated rats

Silica is known to cause an increase in lung surfactant and to promote type II cell hypertrophy and hyperplasia. Two populations of type II cells can be isolated from silica-treated rats: type IIA cells that are similar to normal type II cells and type IIB cells that are larger, contain more surfactant phospholipids, and have increased rates of phospholipid biosynthesis. As much less is known about the influence of silica on the amounts of surfactant proteins (SPs) in type II cells, we examined expression of the genes for all four SPs in types IIA and IIB cells isolated from rats 1, 3, and 7 days after a single intratracheal injection of silica. There was a rapid increase in expression of the SP-A gene in type II cells from the silica-treated animals. SP-A mRNA content was 8- to 10-fold greater in types IIA and IIB cells isolated 1 day after silica injection than in type II cells from saline-injected animals. SP-A mRNA levels were also elevated in the cells isolated on days 3 and 7 after silica injection, but the extent of the increase was less than in the cells isolated on day 1 and declined with time after injection. SP-B, SP-C, and SP-D mRNA levels were 2.5- to 4-fold greater in type IIA cells on day 3 after silica injection than in control type II cells. However, those mRNA levels were not significantly increased in the type IIA cells isolated on days 1 and 7 or in type IIB cells at any time point. These data show that silica causes a rapid and substantial increase in expression of the SP-A gene in type II cells.

Improved motile sperm recovery by a hyperosmotic Percoll gradient

PURPOSE

Our purpose was to investigate whether a new, relatively hyperosmotic Percoll gradient, Enhance-S, can improve total motile sperm recovery rates compared with the commonly used Percoll gradient Perception.

METHODS

Semen specimens from each of 17 donors were divided into two equal aliquots. One part was washed using Percoll Perception, while the other was prepared using Percoll Enhance-S.

RESULTS

Compared to the unwashed specimen, sperm motion characteristics (motility and velocity) improved significantly after Percoll separation using either the Perception or the Enhance-S gradient. There was no difference in motility or velocity in spermatozoa recovered after wash with either of the two preparations. However, the total motile sperm recovery was significantly higher using the Percoll Enhance-S gradient than with the Percoll Perception gradient (P < 0.0024).

CONCLUSION

The new Percoll Enhance-S gradient provides significantly more total motile sperm than the Percoll Perception gradient.

Calpain contributes to silica-induced I kappa B-alpha degradation and nuclear factor-kappa B activation

Both silica and lipopolysaccharide (LPS) induce a rapid degradation of I kappa B alpha, an intracellular inhibitor of the nuclear factor (NF)-kappa B transcription factor. In this report, we demonstrate that MG132, a relatively specific proteasome inhibitor, is capable of suppressing LPS-induced I kappa B alpha degradation and NF-kappa B activation in mouse macrophage line RAW 264.7 cells, but is unable to influence the same induction produced by silica. In contrast, the lysosome inhibitor chloroquine has little effect on I kappa B alpha degradation induced by either silica or LPS. In fact, chloroquine enhances the signal-induced nuclear expression of NF-kappa B p50/p65 heterodimer by inhibiting the resynthesis of I kappa B alpha. With the use of transient transfection of a plasmid that expresses calpastatin, a natural inhibitor for calpain, the silica-induced degradation of I kappa B alpha and NF-kappa B activation was attenuated. In contrast, no inhibition of LPS-induced I kappa B alpha degradation and NF-kappa B activation was observed by the overexpression of calpastatin. This suggests that calpain contributes to silica-induced I kappa B alpha degradation and NF-kappa B activation but not to LPS-induced I kappa B alpha degradation and NF-kappa B activation.

Involvement of NF-kappaB in silica-induced cyclooxygenase II gene expression in rat alveolar macrophages

The role of nuclear factor (NF)-kappaB transcription factor in silica-induced cyclooxygenase (COX) II gene expression was examined in the rat alveolar macrophage cell line NR8383. Our results indicate that NF-kappaB can be activated in this cell line by silica exposure. Suppression of NF-kappaB activation in these cells leads to an attenuation of COX II mRNA accumulation induced by silica. Using an electrophoretic mobility shift assay and a reporter gene assay, we provide evidence that at least two kappaB sites in the 5'-flanking region of the rat COX II gene are involved for silica-induced transcriptional control of the COX II gene. The first motif, -404 GGGGATTCCC -395, is absolutely conserved in sequence and is localized in a similar position among the COX II genes found in humans, rats, and mice. The second motif, -91 GGGGAAAGCC -82, was conserved only in the mouse and rat COX II genes in sequence and in location. Aspirin, a COX inhibitor, was shown to suppress silica-induced NF-kappaB activation. However, prostaglandin E2, one of the important downstream reaction products catalyzed by the COX enzyme, was also shown to attenuate silica-induced NF-kappaB activation by retarding the degradation of silica-induced inhibitor NF-kappaB. These results suggest that an interdependent regulation may exist between NF-kappaB activation and COX or its products.

Differential inductive and suppressive effects of endotoxin and particulate irritants on hepatic and renal cytochrome P-450 expression

Inflammatory stimuli such as bacterial lipopolysaccharide (LPS) have been shown to down-regulate the mRNA and protein expression of hepatic cytochrome P-450 (P-450) isozymes 2C11, 2C12, 2E1 and 3A2 and to induce the mRNA expression of the P-450 4A subfamily. In this study, we examined the effects of irritants on the hepatic and renal expression of P-450 2C11, 2E1 and 3A2 and the 4A subfamily in the rat. Fischer 344 rats were administered doses of SiO2 (Celite), BaSO4, kaolin and LPS intraperitoneally and killed after different times for hepatic and renal RNA and microsome isolation. The administration of each irritant was found to suppress hepatic P-450 2C11 mRNA and protein and to induce P-450 4A1, 4A2 and 4A3 mRNA expression while having no significant effect on P-450 2E1 or 3A2. P-450 4A2, 4A3 and 2E1 mRNAs were all induced in the kidney cortices of the irritant- and LPS-treated rats. The effects of BaSO4 and SiO2 were found to be dose dependent. Chlorzoxazone-6-hydroxylase activity increased in the kidneys of irritant-treated rats, which is consistent with an increased expression of P-450 2E1. All irritants were found to induce the mRNA for the acute-phase protein fibrinogen; however, in contrast to LPS treatment, none of the irritants that were tested induced hepatic inducible nitric oxide synthase mRNA expression. These findings demonstrate the induction of renal P-450 isozymes after irritant and LPS administration. The findings of this study also suggest that different inflammatory stimuli affect the individual P-450 isozymes differentially.

Antisense inhibition of silica-induced tumor necrosis factor in alveolar macrophages

Tumor necrosis factor-alpha (TNFalpha) has been shown to play an important role in the pathogenesis of silicotic fibrosis. In this study, antisense oligonucleotides targeted to TNFalpha mRNA were used to inhibit silica-induced TNFalpha gene expression in alveolar macrophages. To achieve macrophage-specific oligonucleotide delivery, a molecular conjugate consisting of mannosylated polylysine that exploits endocytosis via the macrophage mannose receptor was used. Complexes were formed between the mannosylated polylysine and oligonucleotides and added to the cells in the presence of silica. Enzyme-linked immunoadsorbent assay showed that the complex consisting of the conjugate and antisense oligomer effectively inhibited TNFalpha production, whereas the oligomer alone had much less effect. Reverse transcriptase-polymerase chain reaction analysis revealed that the reduction in TNFalpha secretion was associated with specific ablation of targeted TNFalpha mRNA. The conjugate alone or conjugate complexed with inverted or sense sequence oligonucleotide had no effect. The promoting effect of the conjugate on antisense activity was shown to be due to enhanced cellular uptake of the oligomer via mannose receptor-mediated endocytosis. Cells lacking mannose receptors showed no susceptibility to the conjugate treatment. These results indicate that effective and selective inhibition of macrophage TNFalpha expression can be achieved using the antisense mannosylated polylysine system.

Tetrandrine inhibits signal-induced NF-kappa B activation in rat alveolar macrophages

Tetrandrine is a bisbenzylisoquinoline alkaloid isolated from a natural Chinese herbal medicine. While this alkaloid has been shown to exhibit antifibrotic and anti-inflammatory activities, its mechanism of action is unknown. The present study was designed to investigate the inhibitory effect of tetrandrine on NF-kappa B activation in the alveolar macrophage. Three different provocative stimuli were used to activate NF-kappa B in these cells. The results indicate that tetrandrine can inhibit the activation of NF-kappa B and NF-kappa B-dependent reporter gene expression by LPS, PMA, and silica in a dose-dependent manner. In contrast, at the doses used, tetrandrine did not interfere with Sp-1 DNA binding activity or Sp-1-dependent reporter gene expression in these cells. Western blot analysis suggests that the inhibitory effect of tetrandrine on NF-kappa B activation can be attributed to its ability to suppress signal-induced degradation of I kappa B alpha, a cytoplasmic inhibitor of the NF-kappa B transcription factor.

Mouse in vitro fertilization, embryo development and viability, and human sperm motility in substances used for human sperm preparation for assisted reproduction

OBJECTIVE

To investigate the endotoxin content and effects on mouse IVF and embryo development and human sperm motility of human sperm separation substances.

DESIGN

One-cell and zona-free two-cell mouse embryo bioassays and Limulus Amoebocyte Lysate endotoxin tests and mouse oocyte parthenogenetic activation, IVF, preimplantation and postimplantation embryo development, and human sperm motility were performed in control medium or medium containing Percoll, Nicodenz, or the washings from Sperm Prep sephadex columns.

SETTING

Research Laboratories, Sinai Hospital of Baltimore, Baltimore, Maryland.

MAIN OUTCOME MEASURE(S)

Endotoxin levels, embryo development, and sperm motility.

RESULT(S)

Mouse embryo bioassays indicated negative endotoxin levels in Percoll and Nicodenz but Limulus Amoebocyte Lysate assays had positive gel formation. Mouse IVF and preimplantation development was equivalent in control and Percoll- and Nicodenz-containing medium; none had parthenogenetic properties but postimplantation development was reduced for embryos grown in the presence of Percoll or Nicodenz. Human sperm remained motile in the presence of Percoll or Nicodenz. Sperm Prep column washes were toxic to mouse gametes and embryos and human sperm and had gel formation with the Limulus Amoebocyte Lysate assay.

CONCLUSION(S)

Percoll and Nicodenz, but not Sperm Prep sephadex column washes, were compatible with mouse preimplantation and postimplantation embryo development and human sperm motility.

Silica induces changes in cytosolic free calcium, cytosolic pH, and plasma membrane potential in bovine alveolar macrophages

The mineral-dust induced activation of pulmonary phagocytes is thought to be involved in the induction of severe lung diseases. The activation of bovine alveolar macrophages (BAM) by silica was investigated by flow cytometry. Short-term incubation (< 10 min) of BAM with silica gel and quartz dust particles induced increases in the cytosolic free calcium concentration ([Ca2+]i), decreases in intracellular pH (pHi), and increases in plasma membrane potential (PMP). The extent of these changes was concentration dependent, related to the type of dust and was due to Ca2+ influx from the extracellular medium. An increase in [Ca2+]i was inhibited, when extracellular Ca2+ was removed. Furthermore the calcium signal was quenched by Mn2+ and diminished by the calcium channel blocker verapamil. The protein kinase C specific inhibitor bisindolylmaleimide II (GF 109,203 X) did not inhibit the silica-induced [Ca2+]i rise. In contrast, silica-induced cytosolic acidification and depolarization were inhibited by GF 109,203 X but not by removal of extracellular calcium. Addition of TiO2 particles or heavy metal-containing dusts had no effect on any of the three parameters. Our data suggest the existence of silica-activated transmembrane ion exchange mechanisms in BAM, which might be involved in the specific cytotoxicity of silica by Ca(2+)-dependent and independent pathways.

The protective action of polyvinylpyrrolidone-Percoll during the cryopreservation of mouse 2-cell embryos and its effect on subsequent developmental potential post-thaw in vitro and in vivo

The effects of cryopreservation, in media containing (FS3+) or omitting (FS3) polyvinylpyrrolidone (PVP) in the form of Percoll (PVP-Percoll), on the survival of 2-cell mouse embryos was studied. Survival and zona pellucida disruption post-thaw, growth (assessed by in-vitro culture until the blastocyst stage) and development in vivo (assessed by implantation and living fetus rates and the birth of live progeny) were all investigated. Initial post-thaw survival showed no statistically significant difference (P > 0.05) between FS3+ (91.1 +/- 9.8%) and FS3 (84.5 +/- 6.6%). However, there was a statistically significant (P < 0.05) reduction in the incidence of zona damage when the freezing solution contained PVP-Percoll compared to the control (3.6 +/- 1.0 and 8.7 +/- 0.6% respectively) and a statistically significant (P < 0.05) greater number of embryos developing in vitro to the blastocyst stage (84.8 +/- 7.1 and 72.3 +/- 6.1% respectively). The rates of implantation were not significantly different: 72.2 +/- 7.0% for FS3+ and 51.2 +/- 30.7% for the non-frozen control group. The percentage of live fetuses was also similar between the experimental and control groups: 27.4 +/- 10.6 and 24.3 +/- 11.3% respectively. We conclude that the presence of polymers can protect embryos against cryoinjury and that PVP in the form of PVP-Percoll provides a non-toxic alternative to PVP in its native form, during the cryopreservation of mouse 2-cell embryos.

[The analysis of peripheral blood lymphocytes of patients with silicosis and effects of silica in vitro]

It is well known that patients with silicosis are frequently associated with hyperglobulinemia, RA or PSS. It is also suggested that silica can drive and activated the immune system. In this study, we intended to measure the percentage of CD4+CD45RA+ cells in the peripheral blood of patients with silicosis and to investigate whether silica can actually activate human lymphocytes in vitro or not. Peripheral blood from 45 patients with silicosis was stained with OKT4 and 2H4 monoclonal antibodies, and measured by FACS analysis at 1st day and also checked similarly after 6 days-incubation without patients' sera. The intracellular Ca++ level was also checked after incubation with the normal human lymphocytes with silica by FACS analysis, using Fluo3-AM. CD4+CD45RA+ T cells decreased significantly in number. One to 5 minutes after the incubation with silica, intracellular Ca++ level increased markedly, which means the activation of lymphocytes in vitro. These results revealed that silica can activate human lymphocytes in vitro, but the role in vivo remains to be clarified.

Optimal processing of human umbilical cord blood for clinical banking

Human umbilical cord blood (UCB) has been successfully used as an alternative source of allogeneic hematopoietic stem cells for pediatric transplantation. Clinical banking of UCB requires volume reduction and red cell depletion for cost-effective storage. We have compared processing UCB by Ficoll, Percoll, methylcellulose, gelatin, starch, and red cell lysis. As individual UCB collections vary widely in colony forming cell (CFC) and CD34+ cell content, each UCB (n = 26) was processed by three or more techniques in parallel with Ficoll as the "standard" method. Gelatin gave a consistently high recovery of CFC (92%) and CD34+ cells (86%). Between 0.10-2.50% of the leukocytes in gelatin-treated UCB were CD34+ with an intra-assay variation of 2.1%. Combining data from individual experiments, the correlation between CD34+ and CFC content was excellent (r = 0.77). Lysis rated second in terms of CD34+ and CFC recoveries but is not as practical because of the large volumes involved. Ficoll and Percoll came third but are more expensive and more involved techniques. Starch sedimentation proved to be slow, while methylcellulose processing lost over 60% of CFC and CD34+ cells. After gelatin processing, we calculated 70-mL donations of UCB would contain a mean +/- SD of 9 +/- 2 x 10(8) nucleated cells, 32 +/- 18 x 10(5) CD34+ cells, and 20 +/- 12 x 10(5) CFC with greater than 95% red cell depletion. Recent published computer studies suggest that as few as 2 x 10(5) CD34+ cells may be needed for sustained engraftment of allogeneic marrow in adult transplant recipients. We conclude that average 70-mL UCB donations contain sufficient marrow repopulating cells for adult recipients.

Induction of interleukin-1 and interleukin-8 mRNAs and proteins by TGF beta 1 in rat lung alveolar epithelial cells

The transforming growth factor-beta (TGF-beta) has been shown to increase in lung injury and in fibrotic states of the lung. In the current study, we sought to investigate whether TGF beta 1 induced the expression of IL-1 alpha and IL-8 in rat alveolar epithelial cells. We evaluated TGF beta 1, IL-1 alpha, and IL-8 expression by immunofluorescence in silica-injured and saline-treated control rat lungs. Antibodies to IL-1 alpha, IL-8, and TGF beta 1 showed intense staining in silica-injured lungs as compared to saline-instilled lungs. Primary isolated type II cells from silica-injured lungs showed increased expression of IL-1 alpha as compared to saline-instilled lungs. To evaluate the effects of TGF beta 1, we treated an immortalized rat type II cell-derived cell line (LM5) with 100 pg/ml of TGF beta 1 in serum-free medium for 0-24 hours and analyzed the expression of IL-1 alpha and IL-8 mRNAs and proteins using semiquantitative RT-PCR, Northern blot analysis, Western blot analysis, and immunohistochemistry. Densitometric analysis of Northern blots showed modest constitutive expression of IL-1 alpha gene in untreated control LM5 cells. TGF beta 1 treatment resulted in an increase in IL-1 alpha mRNA, that reached maximum levels (4-fold) by 2 hours and remained elevated for 4-16 hours, with a subsequent decline by 24 hours. Similarly, Northern blot and RT-PCR analysis demonstrated that TGF beta 1 treatment resulted in maximum induction of IL-8 mRNA (6- 8.5-fold) within 1-4 hours. The levels remained elevated for up to 24 hours afterwards. Western blot analysis results further confirmed the expression of both IL-1 alpha and IL-8 proteins by LM5 cells. TGF beta 1 treatment resulted in increased expression of both IL-1 alpha and IL-8 proteins. Immunofluorescence studies demonstrated increased staining of IL-1 alpha by TGF beta 1 as compared to untreated cells. These results suggest that TGF beta 1 may regulate IL-1 alpha and IL-8 expression in alveolar epithelial cells and contribute to polymorphonuclear leukocyte recruitment and lung injury in clinical states with increased TGF beta 1.