A histopathological and stereological study of liver damage in female rats caused by mercury vapor

We examined the possible effects of elemental mercury vapor on the liver of the female rats. We divided the animals into an untreated control group and an experimental group that was exposed to mercury vapor for 45 days. Liver samples were obtained for histological and stereological analysis. The total liver, parenchyma and sinusoid volumes were increased significantly in the mercury vapor treated group compared to controls. Also, the mean density, total number and mean nuclear diameter of hepatocytes, except for binucleated hepatocytes, was decreased in the experimental group compared to controls. Light and electron microscopy revealed alterations of liver structure of the experimental animals compared to controls.     

Simultaneous analysis of the di(2-ethylhexyl)phthalate metabolites 2-ethylhexanoic acid, 2-ethyl-3-hydroxyhexanoic acid and 2-ethyl-3-oxohexanoic acid in urine by gas chromatography–mass spectrometry

A gas chromatographic–mass spectrometric method was developed for the quantitative analysis of the three Di(2-ethylhexyl)phthalate (DEHP) metabolites, 2-ethylhexanoic acid, 2-ethyl-3-hydroxyhexanoic acid and 2-ethyl-3-oxohexanoic acid in urine. After oximation with O-(2,3,4,5,6-pentafluorobenzyl)-hydroxylamine hydrochloride and sample clean-up with Chromosorb P filled glass tubes, all three organic acids were converted to their tert.-butyldimethylsilyl derivatives. Quantitation was done with trans-cinnamic acid as internal standard and GC–MS analysis in the selected ion monitoring mode (SIM). Calibration curves for all three acids in the range from 20 to 1000 μg/l showed correlation coefficients from 0.9972 to 0.9986. The relative standard deviation (RSD) values determined in the observed concentration range were between 1.3 and 8.9% for all three acids. Here we report for the first time the identification of 2-ethyl-3-hydroxyhexanoic acid and 2-ethyl-3-oxohexanoic acid in human urine next to the known DEHP metabolite 2-ethylhexanoic acid. In 28 urine samples from healthy persons we found all three acids with mean concentrations of 56.1±13.5 μg/l for 2-ethylhexanoic acid, 104.8± 80.6 μg/l for 2-ethyl-3-hydroxyhexanoic acid and 482.2± 389.5 μg/l for 2-ethyl-3-oxohexanoic acid.     

Urinary organic acid screening by solid-phase microextraction of the methyl esters

We developed a new sample preparation method for profiling organic acids in urine by GC or GC–MS. The method includes derivatisation of the organic acids directly in the aqueous urine using trimethyloxonium tetrafluoroborate as a methylating agent, extraction of the organic acid methyl esters from the urine by solid-phase microextraction, using a polyacrylate fiber with a thickness of 85 μm and transfer of the methyl esters into the GC or the GC–MS instrument. Desorption of the analytes takes place in the heated injection port. The proposed sample preparation is very simple. There is no need for any evaporation step and for the use of an organic solvent. The risk of contamination and the loss of analytes are minimized. The total sample preparation time prior to GC or GC–MS analysis is about 40 min, and therefore more rapid than other sample preparation procedures. The urinary organic acids are well separated by GC and 29 substances are identified by GC–MS.     

Alteration of the Cell Surface during the Vegetative Cell Cycle of the Unicellular Green Alga Chlamydomonas reinhardtii

Alterations of the cell surface during the vegetative cell cycleof the unicellular green alga Chlamydomonas reinhardtii wereinvestigated using polyclonal antibodies against the purifiedand subsequently deglycosylated insoluble cell wall componentand against a 100 kDa polypeptide of the deglycosylated, chaotrope-solublewall fraction, respectively. Both antibodies recognized epitopeswithin the non-glycosylated domains of a ‘150 kDa’chaotrope-soluble glycoprotein (=GP3B) localized in the outerlayers of the C. reinhardtii cell wall. Immunofluorescence studiesindicated that both antibodies reacted with the surface of ‘late’sporangia (harvested 1 h before liberation of the zoospores),but not with the cell surfaces of released zoospores, growingcells and young sporangia, respectively. After pretreatmentwith aqueous LiCl, however, the cell surfaces of zoospores,growing cells and young sporangia became accessible to theseparticular antibodies. Highly purified preparations of the insolublewall fraction revealed strong immunofluorescence with both antibodiesbut not with the corresponding preimmune sera. Based on thesedata, we concluded that the antigenic sites of the insolubleglycoprotein framework of the C. reinhardtii wall are maskedby LiCl-soluble glycoproteins in single cell stages and youngsporangia, but not or to a lesser extent in the case of themother walls of ‘late’ sporangia. The conclusionwas supported by findings that (I) the multilayered structureof the mother-cell wall was disturbed in ‘late’,but not in young sporangia and that (II) the amounts of chaotropesolublecell wall glycoproteins present in the LiCl-extracts from intactsporangia decreased during ripening of the sporangia. (Received January 10, 1996; Accepted May 27, 1996)     

Immunological Identification of a Putative Precursor of the Insoluble Glycoprotein Framework of the Chlamydomonas Cell Wall

To identify precursors of the insoluble glycoprotein frameworkof the Chlamydomonas cell wall, a polyclonal antibody was raisedagainst the mixture of polypeptides released from the insolublewall fraction by chemical deglycosylation. This antibody preferentiallycross-reacted with a ‘150 kDa’ salt-soluble cellwall glycoprotein. The conclusion that this ‘150 kDa’glycoprotein is a putative precursor of the insoluble cell wallfraction was corroborated by the results of pulse-chase experimentsand by experiments with antibodies raised against the ‘150kDa’ salt-soluble glycoprotein and against its 100 kDadeglycosylation product, respectively. Whereas the antibodyagainst the ‘150 kDa’ glycoprotein preferentiallyrecognized carbohydrate side chains, the antibody against its100 kDa deglycosylation product was found to have essentiallythe same specificity towards glycosylated and deglycosylatedcell wall components as the antibody against the deglycosylationproducts of the insoluble wall fraction. Furthermore, the antibodyagainst the deglycosylated, insoluble wall fraction recognizedalmost the same set of peptide fragments derived by V8 proteasetreatment from the ‘150 kDa’ salt-soluble cell wallglycoprotein and its 100 kDa deglycosylation product, respectively,as the antibody against the 100 kDa deglycosylated cell wallpolypeptide. (Received April 22, 1994; Accepted November 21, 1995)     

Maturation of secretory granules in the endosalpinx one to four days post coitum in sheep

Summary The ultrastructure of granules in the secretory cells of the endosalpinx of 20 Merino ewes was examined on days 1, 2, 3, and 4 post coitum. Based on the different frequency of granules of different size and structure on days one to four post coitum, one can assume that the ovoid, membrane bounded secretory granules mature in five successive stages. In stage I small, electron-lucent vesicles with a finely granulated and filamentous content become apparent, initially in the neighbourhood of the Golgi complex. In stage II the granules become larger and progressively more eletron-dense by an increase of the granulated material. In stage III, the primarily granulated content forms membranes, that lie in characteristic stacks at different angles to one another, separated by electron-dense areas. This structure fragments when the granule comes to lie beneath the surface of the cell (stage IV) and opens into the lumen of the oviduct, where its content is discharged in membrane fragments or vesicles (stage V). This discharge is mainly observed shortly before the egg is transported into the uterus.     

Heart ultrastructure in Lepidurus arcticus pallas (Crustacea,Branchiopoda, Notostraca)

Summary The heart of Lepidurus arcticus consists of an epicardium and a single layer of strongly polarized myocardial cells, 10–50 m thick, with the myofibrillar part facing the epicardium. The Z-bands are diffuse and some Z-material forms attachment plaques. Relaxed sarcomeres show a hexagonal arrangement of thick filaments and 6 thin filaments in orbit, but filaments often diverge in their orientation.The sarcolemma invaginates from both the epicardial and the endocardial side of the cell, forming clefts and T-tubules. The sarcoplasmic reticulum is loosely reticular, cisternae associate with sarcolemma to form large and typical peripheral and interior couplings. The latter are of the button-to-button type and they tend to be located at the A-I level.This work was supported by grants from the Norwegian Research Council for Science and Humanities