Arteriovenous malformation of the stomach

A patient with chronic anemia is presented who radiologically showed prominent rugae of the stomach. Angiography demonstrated an arteriovenous malformation with a large feeding artery and prominent draining veins.     

Hymenolepis diminuta: Worm loss and worm weight loss in long-term infections of the rat

Infections of one and two Hymenolepis diminuta established in newly weaned rats continued to grow for the duration of the experiment (238 days), whereas infections of 5 worms per rat became asymptotic around Day 55 postinfection and remained at or below this level thereafter as shown by biomass and mean weight per worm measurements. Infections of 50 worms established in newly weaned rats became asymptotic around Day 28 postinfection and thereafter worms were lost from the rats. Initially the biomass fell with the loss of worms, but by Day 56 a new lower biomass persisted for the remainder of the infection period. This level was maintained, despite diminishing numbers of worms, due to the growth of surviving individuals to a weight exceeding the original weight at maturity by a factor of more than 2. Experiments using rats that were mature at the time of infection demonstrated that the same response occurred, but approximately 3 weeks earlier.     

Characterization by high performance liquid chromatography of angiotensin peptides in the plasma and cerebrospinal fluid of the dog

A high performance liquid chromatography (HPLC) method is described for the separation of angiotensin (Ang) peptides and their subsequent quantification by radioimmunoassay in plasma and cerebrospinal fluid (CSF). The use of the ion-pair solvent heptafluorobutyric acid in gradient HPLC achieves baseline resolution of Ang I, Ang II, and the C-terminal fragments des-[Asp1]-Ang I, des-[Asp1]-Ang II, des-[Asp1,Arg2]-Ang II and des-[Asp1,Arg2,Val3]-Ang II in approximately 25 min. Recovery of synthetic Ang standards after phenylsilica extraction and HPLC separation was greater than 70% for each peptide in both plasma and CSF. Ang I and Ang II were shown to be the major immunoreactive Ang components in plasma, and Ang II, des-[Asp1,Arg2]-Ang II and des-[Asp1,Arg2,Val3]-Ang II in CSF.     

Induction of sesquiterpene cyclase and suppression of squalene synthetase activities in plant cell cultures treated with fungal elicitor

Addition of elicitor, cell wall fragments of the fungus Phytophthora parasitica, to tobacco cell suspension cultures (Nicotiana tabacum) resulted in the rapid synthesis and secretion of large amounts of antibiotic sesquiterpenoids. Pulse-labeling experiments with [¹⁴C]acetate and [³H] mevalonate demonstrated that the induction of sesquiterpenoid biosynthesis, maximal by 6 to 9 hours after elicitor addition to the cell cultures, was paralleled by a rapid and large decline in the incorporation rate of radioactivity into sterols. Consequently, sterol accumulation was also inhibited upon addition of elicitor to the cell cultures. Sesquiterpene cyclase activity was absent from control cell cultures but induced to a maximum within 10 hours of elicitor addition to the cell cultures. The cyclase activity remained elevated for an additional 30 hours before declining. In contrast, squalene synthetase activity was suppressed to less than 15% of that found in control cells within 7 hours of elicitor addition. Our results suggest that the channeling of isoprenoid intermediates, and especially farnesyl diphosphate, into sesquiterpenoids occurred by a coordinated increase in the sesquiterpene cyclase and a decrease in the squalene synthetase enzyme activities. A reexamination of the data pertaining to the transient induction of 3-hydroxy-3-methylglutaryl coenzyme A reductase activity (EC 1.1.1.34) in elicitor-treated cells suggested that, while the reductase activity was necessary for sesquiterpenoid biosynthesis, it functioned more to maintain a sufficient level of intermediates between mevalonate and farnesyl diphosphate rather than as a rate limiting step controlling the synthesis rate of any one class of isoprenoids.     

Generation of hydroxyeicosatetraenoic acids by human inflammatory cells: analysis by thermospray liquid chromatography-mass spectrometry

Arachidonic acid was converted to a series of hydroxyeicosatetraenoic acids (HETEs) by mixed human inflammatory cells following stimulation with the calcium ionophore A23187. HETEs were purified by a simple one-step extraction procedure followed by HPLC. The HPLC was coupled to a Finnigan quadrupole mass spectrometer using the now commercially available thermospray liquid chromatography-mass spectrometry interface. The HPLC eluant was monitored 'on line' by the mass spectrometer. Soft ionisation occurs, generating intense molecular ion species in the negative ion mode (M - H-:m/z 319) for each of the isomeric HETEs. The (M + H+ - H2O) ion at m/z 303 is the major species in the positive ion spectra of HETEs. Mass spectra were obtained on-line post-HPLC for HETEs formed by the human cells, and the HPLC-MS profile compared with that obtained from standards; species corresponding to the 11-, 9- and 5-HETEs were observed.     

The inhibition of mitochondrial dicarboxylate transport by inorganic phosphate, some phosphate esters and some phosphonate compounds

1. P(i) competitively inhibited succinate oxidation by intact uncoupled mitochondria in the presence of sufficient N-ethylmaleimide to block the phosphate carrier, with a K(i) of 2.5mm. 2. Of a large number of phosphate esters and phosphonate compounds, phenyl phosphate and phenylphosphonate were found to inhibit competitively uncoupled succinate oxidation by intact but not broken mitochondria. By comparison, benzoate was a relatively weak competitive inhibitor of succinate oxidation by intact mitochondria but a relatively potent inhibitor of succinate dehydrogenase. 3. Phenyl phosphate and phenylphosphonate were non-penetrant, and inhibited P(i)-dependent swelling of mitochondria suspended in isosmolar ammonium malate in a manner non-competitive with P(i). The inhibitors did not affect mitochondrial swelling when tested with P(i) alone. 4. It is concluded that: (i) phenyl phosphate and phenylphosphonate behaved as non-penetrant analogues of P(i), since their inhibitory properties were in strict contrast with those of benzoate; (ii) phenyl phosphate and phenylphosphonate interacted with the dicarboxylate carrier but not with the phosphate carrier; (iii) P(i) was effective as a competitive inhibitor of succinate oxidation because of its being either an alternative substrate for the dicarboxylate carrier or competitive with succinate for the intramitochondrial cations as proposed by Harris & Manger (1968).     

Effect of sublethal and lethal temperature on plant cells

Soybean, Glycine max L., and elodea, Elodea canadensis Michx, leaves were exposed to sublethal and lethal temperatures and examined by light microscopy. Loss of chlorophyll and swollen chloroplasts were observed in cells of elodea leaves exposed to sublethal temperatures. At the thermal death point of leaf cells of elodea and soybean, there was a disorganization of the tonoplast membrane, plasmalemma, and chloroplast membranes. Approximately 40% of the cells in elodea and 50% of the cells in soybean leaves exhibited oriteria of cell death when exposed to a temperature which induced necrotic leaf tissue. Plasmolysis of leaf cells of elodea and soybean occurred at lethal temperatures, but did not appear to be the primary cause of cellular death. The primary effect of lethal temperatures on the leaf cells used in these experiments is disintegration of the cellular membranes.     

Calcium ion accumulation and volume changes of isolated liver mitochondria. Reversal of calcium ion-induced swelling

1. The excessive accumulation of Ca²⁺ by mitochondria suspended in an iso-osmotic buffered potassium chloride medium containing oxidizable substrate and phosphate led to extensive swelling and release of accumulated Ca²⁺ from the mitochondria. When the Ca²⁺ was removed from the medium by chelation with ethylene glycol bis(aminoethyl)tetra-acetate, the swelling was reversed in a respiration-dependent contraction. The contracted mitochondria were shown to have regained some degree of respiratory control. 2. The respiration-dependent contraction could be supported by electron transport through a restricted portion of the respiratory chain, and by substrates donating electrons at different levels in the respiratory chain. 3. Respiratory inhibitors appropriate to the substrate present completely inhibited the contraction. Uncoupling agents, and the inhibitors oligomycin and atractyloside, were without effect. 4. When the reversal of swelling had been prevented by respiratory inhibitors, the addition of ATP induced a contraction of the mitochondria. In the absence of added chelating agent the contraction was very slow. The ATP-induced contraction was completely inhibited by oligomycin and atractyloside, was incomplete in the presence of uncoupling agents and was unaffected by respiratory inhibitors. 5. The relationship between the energy requirements of respiration-dependent contraction and the requirements of ion transport and other contractile systems are discussed.     

Subcellular proteomics for determining iron-limited remodeling of plastids in the model diatom Thalassiosira pseudonana (Bacillariophyta)

Diatoms are important primary producers in the world's oceans, yet their growth is constrained in large regions by low bioavailable iron (Fe). Low-Fe stress-induced limitation of primary production is due to requirements for Fe in components of essential metabolic pathways including photosynthesis and other chloroplast plastid functions. Studies have shown that under low-Fe stress, diatoms alter plastid-specific processes, including components of electron transport. These physiological changes suggest changes of protein content and in protein abundances within the diatom plastid. While in silico predictions provide putative information on plastid-localized proteins, knowledge of diatom plastid proteins remains limited in comparison to well-studied model photosynthetic organisms. To address this, we employed shotgun proteomics to investigate the proteome of subcellular plastid-enriched fractions from Thalassiosira pseudonana to gain a better understanding of how the plastid proteome is remodeled in response to Fe limitation. Using mass spectrometry-based peptide identification and quantification, we analyzed T. pseudonana grown under Fe-replete and -limiting conditions. Through these analyses, we inferred the relative quantities of each protein, revealing that Fe limitation regulates major metabolic pathways in the plastid, including the Calvin cycle. Additionally, we observed changes in the expression of light-harvesting proteins. In silico localization predictions of proteins identified in this plastid-enriched proteome allowed for an in-depth comparison of theoretical versus observed plastid-localization, providing evidence for the potential of additional protein import pathways into the diatom plastid.     

Mutations in type 3 reovirus that determine binding to sialic acid are contained in the fibrous tail domain of viral attachment protein sigma1.

The reovirus attachment protein, sigma1, determines numerous aspects of reovirus-induced disease, including viral virulence, pathways of spread, and tropism for certain types of cells in the central nervous system. The sigma1 protein projects from the virion surface and consists of two distinct morphologic domains, a virion-distal globular domain known as the head and an elongated fibrous domain, termed the tail, which is anchored into the virion capsid. To better understand structure-function relationships of sigma1 protein, we conducted experiments to identify sequences in sigma1 important for viral binding to sialic acid, a component of the receptor for type 3 reovirus. Three serotype 3 reovirus strains incapable of binding sialylated receptors were adapted to growth in murine erythroleukemia (MEL) cells, in which sialic acid is essential for reovirus infectivity. MEL-adapted (MA) mutant viruses isolated by serial passage in MEL cells acquired the capacity to bind sialic acid-containing receptors and demonstrated a dependence on sialic acid for infection of MEL cells. Analysis of reassortant viruses isolated from crosses of an MA mutant virus and a reovirus strain that does not bind sialic acid indicated that the sigma1 protein is solely responsible for efficient growth of MA mutant viruses in MEL cells. The deduced sigma1 amino acid sequences of the MA mutant viruses revealed that each strain contains a substitution within a short region of sequence in the sigma1 tail predicted to form beta-sheet. These studies identify specific sequences that determine the capacity of reovirus to bind sialylated receptors and suggest a location for a sialic acid-binding domain. Furthermore, the results support a model in which type 3 sigma1 protein contains discrete receptor binding domains, one in the head and another in the tail that binds sialic acid.