Nano- and microplastics trigger secretion of protein-rich extracellular polymeric substances from phytoplankton

The substantial increase in plastic pollution in marine ecosystems raises concerns about its adverse impacts on the microbial community. Microorganisms (bacteria, phytoplankton) are important producers of exopolymeric substances (EPS), which govern the processes of marine organic aggregate formation, microbial colonization, and pollutant mobility. Until now, the effects of nano- and micro-plastics on characteristics of EPS composition have received little attention. This study investigated EPS secretion by four phytoplankton species following exposure to various concentrations of polystyrene nano- and microplastics (55 nm nanoparticles; 1 and 6 μm microparticles). The 55 nm nanoparticles induced less growth/survival (determined on a DNA basis) and produced EPS with higher protein-to-carbohydrate (P/C) ratios than the exposure to microplastic particles. The amount of DNA from the four marine phytoplankton showed a higher negative linear correlation with increasing P/C ratios, especially in response to nanoplastic exposure. These results provide evidence that marine phytoplankton are quite sensitive to smaller-sized plastics and actively modify their EPS chemical composition to cope with the stress from pollution. Furthermore, the release of protein-rich EPS was found to facilitate aggregate formation and surface modification of plastic particles, thereby affecting their fate and colonization. Overall, this work offers new insights into the potential harm of different-sized plastic particles and a better understanding of the responding mechanism of marine phytoplankton for plastic pollution. The data also provide needed information about the fate of marine plastics and biogenic aggregation and scavenging processes.

Role of Polysaccharides in Diatom Thalassiosira pseudonana and its Associated Bacteria in Hydrocarbon Presence

Diatoms secrete a significant amount of polysaccharides, which can serve as a critical organic carbon source for bacteria. The 2010 Deepwater Horizon oil spill exposed the Gulf of Mexico to substantial amounts of oil that also impacted the phytoplankton community. Increased production of exopolymeric substances was observed after this oil spill. Polysaccharides make up a major fraction of exopolymeric substances; however, their physiological role during an oil spill remains poorly understood. Here, we analyzed the role of polysaccharides in the growth and physiology of the oil-sensitive diatom Thalassiosira pseudonana and how they shape the surrounding bacterial community and its activity in the presence of oil. We found that inhibition of chrysolaminarin synthesis had a negative effect on the growth of T pseudonana and intracellular monosaccharide accumulation, which in turn suppressed photosynthesis by feedback inhibition. In addition, by acting as a carbon reserve, chrysolaminarin helped in the recovery of T pseudonana in the presence of oil. Inhibition of chrysolaminarin synthesis also influenced the bacterial community in the free-living fraction but not in the phycosphere. Exposure to oil alone led to increased abundance of oil-degrading bacterial genera and the activity of exoenzyme lipase. Our data show that chrysolaminarin synthesis plays an important role in the growth and survival of T pseudonana in the presence of oil, and its inhibition can influence the composition and activity of the surrounding bacterial community.

Impact of exposure of crude oil and dispersant (Corexit) on aggregation of extracellular polymeric substances

Spilled oil treated with Corexit dispersant can cause unintended impacts on marine environment systems including altering marine organic matter dynamics; however, impacts on microgels and marine oil snow (MOS) formation are still debated and remain to be fully understood. Extracellular polymeric substances (EPS) are a major source of marine organic carbon for MOS and microgel formation. EPS initial aggregation plays key roles in the oil degrading process and various biogeochemical reactions. Here we used four types of EPS with water accommodated fraction (WAF), chemically-enhanced WAF (CEWAF) and Corexit, to represent potential situations during oil spills and post-application of Corexit. We found that Corexit alone can inhibit EPS aggregation and disperse pre-existing microgels. CEWAF can enhance EPS aggregation with efficiency by up to 80%-100% and more aggregates accumulated within the air-water interface. Additionally, more hydrophobic EPS aggregates showed high resistance to Corexit dispersion while hydrophilic EPS were more sensitive. Effects of oil spills on marine gel particle formation are primarily determined by chemical characteristics (hydrophobicity and protein content) of the constituent EPS. This study offers unique insights for organic particle dynamics and identifies controlling factors for MOS or gel particles associated with oil spills and Corexit dispersant used.

Sunlight induced aggregation of dissolved organic matter: Role of proteins in linking organic carbon and nitrogen cycling in seawater

Organic matter export from the euphotic zone is a key component of oceanic carbon (C) and nitrogen (N) cycles. Although interactions between these two cycles are important, studies on geochemical processes to directly connect them are limited. Here we show that sunlight can induce chemical aggregation of dissolved organic matter (DOM) into high N containing photo-aggregates. The size of microgels in natural coastal seawaters increased by18~25% compared to corresponding dark controls. Within a relatively short time (1 h), the C and N sequestered into the photo-aggregates accounted for 10% and 13% of the bulk particulate C and N, respectively. The N/C ratio of the photo-aggregates was two times higher after sunlight irradiation. Furthermore, we show that the aggregation process was dependent on reactive oxygen species (ROS). To accommodate for the different organic material in the marine environment, we monitored the particle size in various extracellular polymeric substances (EPS) and model biopolymers using flow cytometry, dynamic laser scattering, and scanning electron microscopy. We found that proteins play important roles in light-induced aggregation, which is in contrast to previous views that sunlight can break down DOM and interrupt aggregation. The photo-flocculation process involving organic N provides new insights into DOM assembly, bioavailability, and sedimentation, and thus potentially link the C and N cycles.

Perovskite Nanoparticles Toxicity Study on Airway Epithelial Cells

Research on the toxicity of nanoparticles has developed over recent years due to their increasing prevalence in common everyday materials. Various nanoparticles have been reported to promote and induce mucus secretion, which could potentially lead to airway damages and respiratory complications. Lanthanum strontium manganite (LSM) is a nanoparticle widely used in solar oxidized fuel cells (SOFCs) due to its high electrical conductivity, high electrochemical activity for O₂ reduction reaction, high thermal stability and compatibility of SOFC electrolytes, and most importantly, its microstructural stability and long-term performance. Very few studies have been conducted on LMS's toxicity, thus its effect on airway cells was investigated in this study. After treating trachea cells with increasing concentrations of LSM ranging up to 500 μg/ml, we found that it has a moderate effect on cell viability, ROS production, cytochrome C, and caspase 3 expression. Despite its minimal impact on stated apoptosis-inducing characteristics, LSM illustrated an inhibiting effect on mucus secretion. We obtained a decreasing trend in mucus secretion with an increased concentration of the LSM treatment. Overall, LSM's advancement in SOFCs necessitated a toxicity study, and although it does not show a significant toxicity to trachea cells, LSM reduces mucus secretion, and can potentially interfere with airway clearance.

Extracellular polymeric substances (EPS) producing and oil degrading bacteria isolated from the northern Gulf of Mexico

Sinking marine oil snow was found to be a major mechanism in the transport of spilled oil from the surface to the deep sea following the Deepwater Horizon (DwH) oil spill. Marine snow formation is primarily facilitated by extracellular polymeric substances (EPS), which are mainly composed of proteins and carbohydrates secreted by microorganisms. While numerous bacteria have been identified to degrade oil, there is a paucity of knowledge on bacteria that produce EPS in response to oil and Corexit exposure in the northern Gulf of Mexico (nGoM). In this study, we isolated bacteria from surface water of the nGoM that grow on oil or Corexit dispersant. Among the 100 strains isolated, nine were identified to produce remarkable amounts of EPS. 16S rRNA gene analysis revealed that six isolates (strains C1, C5, W10, W11, W14, W20) belong to the genus Alteromonas; the others were related to Thalassospira (C8), Aestuariibacter (C12), and Escherichia (W13a). The isolates preferably degraded alkanes (17–77%), over polycyclic aromatic hydrocarbons (0.90–23%). The EPS production was determined in the presence of a water accommodated fraction (WAF) of oil, a chemical enhanced WAF (CEWAF), Corexit, and control. The highest production of visible aggregates was found in Corexit followed by CEWAF, WAF, and control; indicating that Corexit generally enhanced EPS production. The addition of WAF and Corexit did not affect the carbohydrate content, but significantly increased the protein content of the EPS. On the average, WAF and CEWAF treatments had nine to ten times more proteins, and Corexit had five times higher than the control. Our results reveal that Alteromonas and Thalassospira, among the commonly reported bacteria following the DwH spill, produce protein rich EPS that could have crucial roles in oil degradation and marine snow formation. This study highlights the link between EPS production and bacterial oil-degrading capacity that should not be overlooked during spilled oil clearance.

The impact of nanoplastics on marine dissolved organic matter assembly

The environmental impact of nanoplastics (NPs) released into natural aquatic surroundings is an increasing concern. NPs are widely generated from our daily waste disposal and eventually reach the ocean, wherein consequent influences on aquatic environments remain unclear. In this regard, there are few studies investigating NP-related ecological impacts. Comprising one of Earth's major carbon pools, marine dissolved organic matter (DOM) serves an essential role in global carbon dynamics. The spontaneous assembly of DOM into particulate organic matter (POM) plays important roles in the marine carbon cycle, and is involved in hemostasis of various ecological communities. Here, we report that 10 ppb NPs (polystyrene/polymethyl methacrylate, 25 nm) appeared in a water column accelerate the kinetic assembly rate of DOM-POM transition. NPs with various characteristics show similar influences on DOM assembly, and seawater samples collected from disparate sites were used to further confirm this unanticipated phenomenon. In this study, we demonstrated that hydrophobic interactions contribute to the facilitation of NP-DOM aggregations. Our results illustrate that NPs alter DOM-POM assembly, which may potentiate unanticipated perturbation to the largest marine carbon pool. Such effects would warrant increased vigilance on current practices of plastic usage and disposal.

CeO2 nanoparticles attenuate airway mucus secretion induced by TiO2 nanoparticles

Nanotoxicity studies associated with various nanoparticles (NPs) have attracted intense research interest due to the broader applications of nanoparticles in our daily lives. The exposure of nanoparticles can lead to hypersecretion and accumulation of airway mucus which are closely associated with many respiratory diseases. Titanium dioxide (TiO2), one of the PM10 components, is a major NP that is widely utilized in many commercial products. Our previous study established the connection between induced airway mucus secretion and TiO2 NPs. However, the countermeasure to reduce the harmful effects of TiO2 NPs, especially airway mucus secretion, remains unexplored. One of the potential candidates to reduce airway mucus secretion is cerium oxide (CeO2) NPs. It has been reported that CeO2 NPs can protect cells by diminishing ROS and inflammatory responses. Herein, our study shows that CeO2 NPs are able to reduce cytosolic Ca2+ changes and mitochondrial damage caused by TiO2 NPs. Our results provide the evidence that hypersecretion of mucus and apoptosis progression induced by TiO2 NPs can be attenuated by CeO2 NPs. This study highlights the potential capacity of CeO2 NPs as a supplementary material for TiO2 NPs applications in the future.

Effect of Engineered Nanoparticles on Exopolymeric Substances Release from Marine Phytoplankton

Engineered nanoparticles (ENPs), products from modern nanotechnologies, can potentially impact the marine environment to pose serious threats to marine ecosystems. However, the cellular responses of marine phytoplankton to ENPs are still not well established. Here, we investigate four different diatom species (Odontella mobiliensis, Skeletonema grethae, Phaeodactylum tricornutum, Thalassiosira pseudonana) and one green algae (Dunaliella tertiolecta) for their extracellular polymeric substances (EPS) release under model ENP treatments: 25 nm titanium dioxide (TiO₂), 10-20 nm silicon dioxide (SiO₂), and 15-30 nm cerium dioxide (CeO₂). We found SiO₂ ENPs can significantly stimulate EPS release from these algae (200-800%), while TiO₂ ENP exposure induced the lowest release. Furthermore, the increase of intracellular Ca²⁺ concentration can be triggered by ENPs, suggesting that the EPS release process is mediated through Ca²⁺ signal pathways. With better understanding of the cellular mechanism mediated ENP-induced EPS release, potential preventative and safety measures can be developed to mitigate negative impact on the marine ecosystem.

Corexit, oil and marine microgels

Corexit, an EPA-approved chemical dispersant, was intensively used during the 2010 Deepwater Horizon Oil Spill in the Gulf of Mexico. Current studies surrounding Corexit have mainly focused on its toxicity and oil removal capacity. The potential impact of Corexit on the surface ocean carbon dynamics has remained largely unknown. The spontaneous assembly of DOM (dissolved organic matter) polymers into microgels (POM, particulate organic matter) was demonstrated previously that it can influence various critical processes, such as colloidal pump, microbial loops, and nutrition availability in the surface ocean. Here, we report that Corexit alone can significantly inhibit DOM microgel formation and reduce the stability of pre-existing microgels. However, Corexit and oil, Chemically Enhanced Water Accommodated Fraction (CEWAF), could effectively facilitate DOM microgel formation. The unanticipated disturbance of Corexit and oil spills on the critical DOM-POM continuum warrant particular caution and thus should be considered for future application of Corexit during oil spills.

Light-induced aggregation of microbial exopolymeric substances

Sunlight can inhibit or disrupt the aggregation process of marine colloids via cleavage of high molecular weight compounds into smaller, less stable fragments. In contrast, some biomolecules, such as proteins excreted from bacteria can form aggregates via cross-linking due to photo-oxidation. To examine whether light-induced aggregation can occur in the marine environment, we conducted irradiation experiments on a well-characterized protein-containing exopolymeric substance (EPS) from the marine bacterium Sagitulla stellata. Our results show that after 1 h sunlight irradiation, the turbidity level of soluble EPS was 60% higher than in the dark control. Flow cytometry also confirmed that more particles of larger sized were formed by sunlight. In addition, we determined a higher mass of aggregates collected on filter in the irradiated samples. This suggests light can induce aggregation of this bacterial EPS. Reactive oxygen species hydroxyl radical and peroxide played critical roles in the photo-oxidation process, and salts assisted the aggregation process. The observation that Sagitulla stellata EPS with relatively high protein content promoted aggregation, was in contrast to the case where no significant differences were found in the aggregation of a non-protein containing phytoplankton EPS between the dark and light conditions. This, together with the evidence that protein-to-carbohydrate ratio of aggregates formed under light condition is significantly higher than that formed under dark condition suggest that proteins are likely the important component for aggregate formation. Light-induced aggregation provides new insights into polymer assembly, marine snow formation, and the fate/transport of organic carbon and nitrogen in the ocean.

The glutathione transferase of Nicotiana benthamiana NbGSTU4 plays a role in regulating the early replication of Bamboo mosaic virus

Bamboo mosaic virus (BaMV) is a single-stranded positive-sense RNA virus. One of the plant glutathione S-transferase (GST) genes, NbGSTU4, responds as an upregulated gene in Nicotiana benthamiana post BaMV infection. In order to identify the role of NbGSTU4 in BaMV infection, the expression of NbGSTU4 was knocked down using a virus-induced gene silencing technique or was transiently expressed in N. benthamiana in BaMV inoculation. The results show a significant decrease in BaMV RNA accumulation when the expression level of NbGSTU4 is reduced; whereas the viral RNA accumulation increases when NbGSTU4 is transiently expressed. Furthermore, this study identified that the involvement of NbGSTU4 in viral RNA accumulation occurs by its participation in the viral early replication step. The findings show that the NbGSTU4 protein expressed from Escherichia coli can interact with the 3' untranslated region (UTR) of the BaMV RNA in vitro in the presence of glutathione (GSH). The addition of GSH in the in vitro replication assay shows an enhancement of minus-strand but not plus-strand RNA synthesis. The results suggest that the plant GST protein plays a role in binding viral RNA and delivering GSH to the replication complex to create a reduced condition for BaMV minus-strand RNA synthesis.

The silencing suppressor P25 of Potato virus X interacts with Argonaute1 and mediates its degradation through the proteasome pathway

Previous evidence has indicated that the P25 protein encoded by Potato virus X (PVX) inhibits either the assembly or function of the effector complexes in the RNA silencing-based antiviral defence system (Bayne et al., Cell-to-cell movement of Potato Potexvirus X is dependent on suppression of RNA silencing. Plant J.44, 471-482). This finding prompted us to investigate the possibility that P25 targets the Argonaute (AGO) effector nuclease of RNA silencing. Co-immunoprecipitation and Western blot analysis indicated that there is a strong interaction between P25 and AGO1 of Arabidopsis when these proteins are transiently co-expressed in Nicotiana benthamiana. P25 also interacts with AGO1, AGO2, AGO3 and AGO4, but not with AGO5 and AGO9. As an effective suppressor, the amount of AGO1 accumulated in the presence of P25 was dramatically lower than that infiltrated with HcPro, but was restored when treated with a proteasome inhibitor MG132. These findings are consistent with the idea that RNA silencing is an antiviral defence mechanism and that the counter-defence role of P25 is through the degradation of AGO proteins via the proteasome pathway. Further support for this idea is provided by the observation that plants treated with MG132 are less susceptible to PVX and its relative Bamboo mosaic virus.

Expressing a bacterial mercuric ion binding protein in plant for phytoremediation of heavy metals

A specific mercuric ion binding protein (MerP) originating from transposon TnMERI1 of Bacillus megaterium strain MB1 isolated from Minamata Bay displayed good adsorption capability for a variety of heavy metals. In this study, the Gram-positive MerP protein was expressed in transgenic Arabidopsis to create a model system for phytoremediation of heavy metals. Under control of an actin promoter, the transgenic Arabidpsis showed higher tolerance and accumulation capacity for mercury, cadium and lead when compared with the control plant. Results from confocal microscopy analysis also indicate that MerP was localized at the cell membrane and vesicles of plant cells. The developed transgenic plants possessing excellent metal-accumulative ability could have potential applications in decontamination of heavy metals.

Distribution of CAG repeat size in the dentatorubral and pallidoluysian atrophy (DRPLA) gene in a normal population in Taiwan

Dentatorubral and pallidoluysian atrophy (DRPLA) is an autosomal dominant neurodegenerative disorder with expansion of trinucleotide CAG repeats in the coding region of the gene. Expansion of the repeat tract beyond the normal range produces gene products with extended polyglutamine tracts. In this study, we analyzed the distribution of the CAG repeats in the DRPLA alleles in a normal Taiwanese population. We observed 15 different alleles and found that the range of the CAG repeat number was from 7-21. The most frequent allele contained 15 CAG repeats that represented 20% of the total analyzed alleles, followed by the 17 repeats (15.8%). The heterozygosity rate of this locus was 88%. Twelve parents-to-children transmissions of the DRPLA alleles in a Machado-Joseph disease family appeared to be normal without any alteration of the CAG repeat numbers. Phenotypes of DRPLA overlapped those of autosomal dominant cerebellar ataxia (ADCA). In order to identify DRPLA patients in Taiwan, we screened six autosomal dominant cerebellar ataxia patients without expansion in known spinocerebellar ataxia genes. All six patients had the repeat numbers within the normal range; thus, the possibility of DRPLA could be excluded.

Complex refractive-index measurement based on Fresnel's equations and the uses of heterodyne interferometry

The phase difference between s and p polarization of the light reflected from a material is used for measuring the material's complex refractive index. First, two phase differences that correspond to two different incidence angles are measured by heterodyne interferometry. Then these two phase differences are substituted into Fresnel's equations, and a set of simultaneous equations is obtained. Finally, the equations are solved by use of a personal computer by a numerical analysis technique, and the complex refractive index of the material can be estimated.

Improved technique for measuring small angles

Based on the total-internal-reflection effect and heterodyne interferometry, an improved technique for measuring small angles is proposed. This technique not only expands the measurement range but it also improves measurement performances. Its validity is demonstrated.

Refractive-index measurement based on the effects of total internal reflection and the uses of heterodyne interferometry

A new method for measuring the refractive index is presented. First, the phase difference between s and p polarizations that is due to the total internal reflection is measured by heterodyne interferometry. Then, substituting this phase difference into the Fresnel equations, we can obtain the refractive index of the test medium.

Malignant lymphoma presenting as tracheal tumor: a case report

A 66-year-old male presented with dyspnea and cough for 1 month. Fiberoptic bronchoscopy disclosed a huge tumor over the posterior wall of the trachea 1 cm below the vocal cord and biopsy pathology was diffuse, small cleaved lymphoma. Primary malignant lymphoma of the trachea is extremely rare. Its clinical course varies widely, and has no accepted standard of management. We describe herein the whole clinical course of this patient, which is not similar to previous reports. The relation of primary tracheal lymphoma to mucosa-associated lymphoid tissue (MALT) is also discussed.

[Diagnostic value of ultrasonically guided lung aspiration in pneumonia]

To determine the diagnostic value of ultrasonic lung aspiration for patients with pneumonia, 60 patients with a tentative diagnosis of pneumonia were included in this study. After recording ultrasonographic findings, lung aspiration was done with a spinal needle and aspirated specimens were sent for Papanicolaou, May-Giemsa, acid fast, and Gram stains. The remaining specimens were sent for bacterial, mycobacterial and fungal culture. Twelve patients were excluded from the study because of the final diagnosis of non-infectious pulmonary diseases. In 28 cases of bacterial pneumonia, the diagnostic sensitivity of smear was 50% and culture 61%. The overall sensitivity of needle aspiration and culture was 71%. In 11 cases of bacterial pneumonia with a negative bacterial culture result, 7 cases were afebrile at the time of examination. To increase the diagnostic yield, needle aspiration should be performed at the acute stage of bacterial pneumonia. In 15 cases of pulmonary tuberculosis, the diagnostic rate of acid-fast smear was 47% and mycobacterial culture was 46%. The overall sensitivity of smear and culture was 60%. The diagnostic rate of needle biopsy was 75% and cytologic examination was 77%. Needle biopsy and cytologic examination enhanced the diagnostic rate of sputum-negative pulmonary tuberculosis. Cryptococcosis was documented by smear and needle biopsy in all of the five cases of cryptococcosis. Cryptococcosis is not easily detected by routine cytologic examination, and clinical information is still necessary to enhance the diagnostic rate. Our results show that ultrasonically guided lung aspiration is a technique with a high diagnostic yield and a low complication rate for various types of pneumonia. It is especially useful for patients without satisfactory clinical responses or without accurate microbiologic diagnosis.

Tissue targeting of multivalent Le(x)-terminated N-linked oligosaccharides in mice

The target site for N-linked biantennary and triantennary oligosaccharides containing multiple terminal Le(x) determinants was analyzed in mice. N-linked oligosaccharides containing a single tert-butoxycarbonyl-tyrosine attached to the reducing end were used as synthons for human milk alpha-3/4-fucosyltransferase to prepare multivalent Le(x) (Gal beta 1-4[Fuc alpha 1-3]GlcNAc) terminated tyrosinamide oligosaccharides. The oligosaccharides were radioiodinated and examined for their pharmacokinetics and biodistribution in mice. The liver was the major target site in mice at 30 min, which accumulated 18% of the dose for Le(x) biantennary compared with 6% for a nonfucosylated Gal biantennary. By comparison, Le(x)- and Gal-terminated triantennary accumulated in the liver with a targeting efficiency of 66 and 59%, respectively. The liver targeting of Le(x)-biantennary was partially blocked by co-administration with either galactose or L-fucose whereas Le(x) triantennary targeting was only reduced by co-administration with galactose. In contrast to these results in mice, in vivo experiments performed in rats established that both Le(x) and Gal terminated biantennary target the liver with nearly identical efficiency (6-7%). It is concluded that the asialoglycoprotein receptor in mice preferentially recognize Le(x) biantennary over Gal biantennary, whereas little or no differentiation exists in rats. Thereby, the mouse asialoglycoprotein receptor apparently possesses additional binding pockets that accommodate a fucose residue when presented as Le(x).

Energy charge and mitotic activity in regenerating rat liver during parenteral nutrition

The relationship among parenteral nutrition, hepatic energy charge, and mitotic activity was investigated in partially hepatectomized rats fed diets based on glucose, ketone bodies, and saline (starvation). Male Sprague-Dawley rats underwent 70% hepatectomy and jugular vein catheterization for parenteral feeding. All rats were infused with saline for 6 hours, then randomly assigned to one of three parenteral infusions. Rats received either 0.9% saline only (group A rats), 25% glucose + 4% amino acid (group B rats), or 18% monoacetoacetin + 7% glucose + 4% amino acid (group C rats). Three rats receiving saline infusion were killed at 2, 4, and 6 hours after surgery, and three rats from each diet group were killed at 2- to 4-hour intervals from 10 through 32 hours. Hepatic energy charge and mitotic index were measured at each time point. Energy charge was similar for each treatment until 18 hours but was depressed from 6 through 16 hours and began to increase between 16 and 18 hours. Energy charge at 22 hours for group B rats was significantly higher than energy charge for group A and C rats. This difference was maintained through 32 hours. Mitosis started between 24 and 26 hours for all treatments, and group A and C rats exhibited a much higher mitotic index than did group B rats. Adenosine triphosphate was the main driving force for changes in energy charge. The data showed that energy charge and mitotic index were inversely related. It is speculated that high energy charge may negatively influence activity of enzymes inasmuch as activity of these enzymes is altered by phosphorylation-dephosphorylation.

In vivo targeting function of N-linked oligosaccharides with terminating galactose and N-acetylgalactosamine residues

N-Linked biantennary, triantennary, and core fucosylated biantennary oligosaccharides were isolated from animal glycoproteins and derivatized at their reducing end with Boc-tyrosine. The terminal Gal residues were enzymatically removed and replaced with GalNAc. Tyrosinamide-oligosaccharides were radioiodinated and administered intravenously to mice. Pharmacokinetic and biodistribution studies revealed structure-dependent differences in the steady-state volume of distribution, total body clearance rate, and targeting efficiency. Tyrosinamide-oligosaccharides were found to resist metabolism relative to a natural triantennary glycopeptide which was rapidly degraded in vivo. Triantennary oligosaccharides containing terminal Gal or Gal-NAc targeted the liver efficiently whereas biantennary oligosaccharides containing terminal Gal residues and differing only in their core fucosylation avoided recognition by the asialoglycoprotein receptor and were cleared unmetabolized by renal filtration. In contrast, biantennary oligosaccharides containing terminal Gal-NAc residues targeted the liver with much greater efficiency than Gal-terminated triantennary oligosaccharide. Core fucosylation reduced the metabolism rate of tyrosinamide-biantennary in the liver. The results establish the utility of tyrosinamide-oligosaccharides as probes to analyze the ligand specificity of mammalian lectins in vivo and demonstrate that a GalNAc-terminated biantennary is a potent ligand for the asialoglycoprotein receptor.

Pulmonary carcinosarcoma: diagnostic approach by fine needle aspiration biopsy

Carcinosarcoma of the lung is an exceedingly uncommon malignancy, possessing both malignant epithelial and mesenchymal elements. There are less than 100 cases reported in the English literature to date. Most of them were diagnosed by autopsy and surgery. Now we present a detailed report of a case with peripheral variant carcinosarcoma diagnosed by percutaneous needle biopsy under sonographic guidance. The clinical, pathologic and immunohistochemical hallmarks of this unique tumor are also reviewed.

The effect of platelet-activating factor on histamine release from guinea pig peritoneal mast cells

The effect of platelet-activating factor (PAF) on histamine release from the peritoneal mast cells of male guinea pigs at 4 weeks of age and one week of age (weaning) was investigated. PAF as well as compound 48/80 and concanavalin A were not found to release histamine from the mast cells of either age of guinea pigs. On the other hand, Ca2+ ionophore A23187 showed a significant, concentration-dependent histamine release from the mast cells obtained from guinea pig of either age group. PAF (3 x 10(-7) - 3 x 10(-6) g/ml) significantly inhibited the histamine release induced by Ca2+ ionophore A23187 from the mast cells of guinea pigs at one week of age, but not from those of the older ones. Such an inhibition was not seen with lyso-PAF in either age group. CV-3988, a PAF antagonist, neutralized the inhibitory effect of PAF on the A23187-induced histamine release from the mast cells of guinea pigs at one week of age. These results indicate that PAF does not have a histamine-liberating action on guinea pig peritoneal mast cells, and that PAF inhibits the effect of A23187 on histamine release from mast cells through activation of PAF receptor in guinea pigs at one week of age.