scholarly journals Studies in vitro on the effects of 1H,2H,4H(5H)-octafluorocyclohexane and 1H,4H(2H)-nonafluorocyclohexane on enzymes and organelles

1969 ◽  
Vol 114 (4) ◽  
pp. 785-792 ◽  
Author(s):  
Jayasree Nath ◽  
H G Bray
Keyword(s):  
Adenosine Triphosphatase ◽  
Marked Decrease ◽  
Reductase Activity ◽  
Electron Microscopic Examination ◽  
Electron Microscopic ◽  
Toxic Compound ◽  
Marked Inhibition ◽  
Liver Homogenates ◽  
Nadh Cytochrome

A comparison has been made of the effect of 1H,2H,4H(5H)-octafluorocyclohexane, which is highly toxic (LD50 17mg./kg. in rats), and of 1H,4H(2H)-nonafluorocyclohexane, which is relatively non-toxic (LD50>440mg./kg. in rats), on the respiration of rat liver homogenates and mitochondria in vitro. 1H,2H,4H(5H)-Octafluorocyclohexane strongly inhibited the respiration of both homogenates and mitochondria, but neither compound had any significant effect on glycolysis or on glutamate dehydrogenase or NADH–cytochrome c reductase activity. 1H,2H,4H(5H)-Octafluorocyclohexane, however, caused a very marked inhibition of cytochrome oxidase activity, causing an almost complete lesion in this region of the respiratory chain. 1H,4H(2H)-Nonafluorocyclohexane was without effect in this respect. A marked decrease in turbidity of mitochondrial suspensions at 520nm. was caused by addition of both compounds, the effect being greater with 1H,2H,4H(5H)-octafluorocyclohexane. ATP, Mg2+ and bovine serum albumin did not reverse these changes. Mitochondrial adenosine triphosphatase activity was increased twofold by the toxic compound, but only slightly by the non-toxic compound. Electron-microscopic examination of mitochondria treated with 1H,2H,4H(5H)-octafluorocyclohexane revealed gross morphological damage, whereas the effect of 1H,4H(2H)-nonafluorocyclohexane appeared to be merely to cause swelling. The results obtained account, to some extent at any rate, for the toxic effects of 1H,2H,4H(5H)-octafluorocyclohexane.

scholarly journals In vitro formation of osteoclasts from long-term cultures of bone marrow mononuclear phagocytes.

1982 ◽  
Vol 156 (6) ◽  
pp. 1604-1614 ◽  
Author(s):  
E H Burger ◽  
J W Van der Meer ◽  
J S van de Gevel ◽  
J C Gribnau ◽  
G W Thesingh ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Electron Microscopic Examination ◽  
Osteoclast Formation ◽  
Mononuclear Phagocytes ◽  
Long Bone ◽  
Embryonic Liver ◽  
Blood Monocytes ◽  
Electron Microscopic ◽  
Embryonic Mouse

The origin of osteoclasts was studied in an in vitro model using organ cultures of periosteum-free embryonic mouse long-bone primordia, which were co-cultured with various cell populations. The bone rudiments were freed of their periosteum-perichondrium by collagenase treatment in a stage before cartilage erosion and osteoclast formation, and co-cultured for 7 d with either embryonic liver or mononuclear phagocytes from various sources. Light and electron microscopic examination of the cultures showed that mineralized matrix-resorbing osteoclasts developed only in bones co-cultured with embryonic liver or with cultured bone marrow mononuclear phagocytes but not when co-cultured with blood monocytes or resident or exudate peritoneal macrophages. Osteoclasts developed from the weakly adherent, but not from the strongly adherent cells of bone marrow cultures, whereas 1,000 rad irradiation destroyed the capacity of such cultures to form osteoclasts. In bone cultures to which no other cells were added, osteoclasts were virtually absent. Bone-resorbing activity of in vitro formed osteoclasts was demonstrated by 45Ca release studies. These studies demonstrate that osteoclasts develop from cells present in cultures of proliferating mononuclear phagocytes and that, at least in our system, monocytes and macrophages are unable to form osteoclasts. The most likely candidates for osteoclast precursor cells seem to be monoblasts and promonocytes.

scholarly journals Mice Deficient in the Axonemal Protein Tektin-t Exhibit Male Infertility and Immotile-Cilium Syndrome Due to Impaired Inner Arm Dynein Function

2004 ◽  
Vol 24 (18) ◽  
pp. 7958-7964 ◽  
Author(s):  
Hiromitsu Tanaka ◽  
Naoko Iguchi ◽  
Yoshiro Toyama ◽  
Kouichi Kitamura ◽  
Tohru Takahashi ◽  
...  
Keyword(s):  
Physiological Role ◽  
Electron Microscopic Examination ◽  
Electron Microscopic ◽  
Vitro Fertilization ◽  
Homozygous Mutant ◽  
Causal Genes ◽  
And Function ◽  
Ciliary Dyskinesia

ABSTRACT The haploid germ cell-specific Tektin-t protein is a member of the Tektin family of proteins that form filaments in flagellar, ciliary, and axonemal microtubules. To investigate the physiological role of Tektin-t, we generated mice with a mutation in the tektin-t gene. The homozygous mutant males were infertile, while the females were fully fertile. Sperm morphology and function were abnormal, with frequent bending of the sperm flagella and marked defects in motility. In vitro fertilization assays showed that the defective spermatozoa were able to fertilize eggs. Electron microscopic examination showed that the dynein inner arm structure was disrupted in the sperm flagella of tektin-t-deficient mice. Furthermore, homozygous mutant mice had functionally defective tracheal cilia, as evidenced by altered dynein arm morphology. These results indicate that Tektin-t participates in dynein inner arm formation or attachment and that the loss of Tektin-t results in impaired motility of both flagella and cilia. Therefore, the tektin-t gene is one of the causal genes for immotile-cilium syndrome/primary ciliary dyskinesia.

scholarly journals Phosphorylation of vimentin in mitotically selected cells. In vitro cyclic AMP-independent kinase and calcium-stimulated phosphatase activities.

1989 ◽  
Vol 108 (1) ◽  
pp. 67-78 ◽  
Author(s):  
R M Evans
Keyword(s):  
Phosphatase Activity ◽  
Kinase Activity ◽  
Electron Microscopic Examination ◽  
Intermediate Filament Protein ◽  
Electron Microscopic ◽  
Intact Cells ◽  
Activity Peak ◽  
Casein Kinases ◽  
Phosphopeptide Mapping

The phosphorylation of the intermediate filament protein vimentin was examined under in vitro conditions. Cell cytosol and Triton-insoluble cytoskeleton preparations from nonmitotic and mitotically selected mouse L-929 cells exhibited vimentin kinase activity that is apparently cAMP and Ca2+ independent. The level of vimentin kinase activity was greater in preparations from mitotically selected cells than nonmitotic cells. Addition of Ca2+ to mitotic cytosol decreased net vimentin phosphorylation. Dephosphorylation experiments indicated that there is phosphatase activity in these preparations which is stimulated by addition of Ca2+. Fractionation of cytosol from nonmitotic cells on DEAE-Sephacel and phosphocellulose revealed a single major vimentin kinase activity (peak I). Fractionation of cytosol from mitotically selected cells yielded a similar activity (peak I) and an additional vimentin kinase activity (peak II) that was not found in nonmitotic preparations. Based on substrate specificity and lack of inhibition to characteristic inhibitors, the semipurified peak I and II vimentin kinase activities appear to be cAMP-independent enzymes that are distinct from casein kinases I and II. Phosphopeptide mapping studies indicated that both peak I and peak II vimentin kinases phosphorylate tryptic peptides in the NH2-terminal region of vimentin that are phosphorylated in intact cells. Electron microscopic examination of reconstituted vimentin filaments phosphorylated with both semipurified kinases indicated that phosphorylation induced filament disassembly. These experiments indicate that the increased phosphorylation of vimentin during mitosis may be catalyzed by a discrete cAMP-independent protein kinase. In addition, preparations from mitotic cells exhibited a Ca2+-stimulated phosphatase activity, suggesting that Ca2+ may play a regulatory role in vimentin dephosphorylation during mitosis.

Influence of several drugs on the in vivo and in vitro activity of mammalian hepatic azo-reductase

1968 ◽  
Vol 46 (4) ◽  
pp. 367-371 ◽  
Author(s):  
John V. Burba
Keyword(s):  
Guinea Pigs ◽  
Marked Decrease ◽  
Reductase Activity ◽  
Sulfanilic Acid ◽  
In Vitro Activity ◽  
Appreciable Increase ◽  
Azo Reductase

The ability of a variety of drugs to influence liver azo-reductase activity of rabbits, rats, and guinea pigs in vitro was determined. Only nitrofurantoin showed a marked stimulatory activity in the three species. There was no appreciable inhibitory activity with any of the drugs tested. Determination of azo-reductase activity in vivo after pretreatment of the animals with phenobarbital and nitrofurantoin showed that there was an appreciable increase only in the azo-reductase activity of rats with phenobarbital, and only rabbits showed a marked decrease in azo-reductase activity with nitrofurantoin. Under the same conditions there was an appreciable increase in the excretion of N-acetylated sulfanilic acid by phenobarbital-pretreated rats and guinea pigs, while with nitrofurantoin rabbits showed an increase and rats a large decrease in the excretion of N-acetylated sulfanilic acid.

A light and electron microscope study of the interaction of soil bacteria with Phytophthora cinnamomi Rands

1977 ◽  
Vol 23 (11) ◽  
pp. 1518-1525 ◽  
Author(s):  
N. Malajczuk ◽  
H. J. Nesbitt ◽  
A. R. Glenn
Keyword(s):  
Soil Bacteria ◽  
Phytophthora Cinnamomi ◽  
Electron Microscopic Examination ◽  
Electron Microscopic ◽  
Microbial Association ◽  
Reproductive Structures ◽  
Streptomyces Spp ◽  
Lysis Inhibition ◽  
Zoospore Production

Light- and electron-microscopic examination showed that bacteria became associated with the hyphae and asexual reproductive structures of P. cinnamomi in soil. In suppressive soils this association appears to be correlated with hyphal lysis, inhibition of zoospore production, and sporangial breakdown. One notable feature of the microbial association between P. cinnamomi and soil bacteria is the formation of extensive slime material. Many of the bacteria isolated from the fungal hyphosphere display antagonism to the growth of P. cinnamomi in vitro. The bacteria are morphologically varied and include Pseudomonas, Bacillus, and Streptomyces spp. These observations suggest that the appropriate manipulation of the antagonistic bacteria may provide a means of biological control of P. cinnamomi.

scholarly journals Are cross-bridging structures involved in the bundle formation of intermediate filaments and the decrease in locomotion that accompany cell aging?

1985 ◽  
Vol 100 (5) ◽  
pp. 1466-1473 ◽  
Author(s):  
E Wang
Keyword(s):  
Intermediate Filaments ◽  
Electron Microscopic Examination ◽  
Time Lapse ◽  
Cell Aging ◽  
Electron Microscopic ◽  
Cell Locomotion ◽  
Wide Range ◽  
Filament Bundles ◽  
Large Filament

Five different fibroblast strains derived from donors of a wide range of ages were used for investigation of senescence-associated changes in the organization of intermediate filaments (IFs) and the activity of cell locomotion. Results of immunofluorescence microscopy demonstrate that, in large and flat in vitro aged fibroblasts, vimentin-containing IFs are distributed as unusually organized large bundles. Electron microscopic examination shows that these large bundles are indeed composed of filaments of 8-10 nm. Such a profile of large bundles is rarely seen in young fibroblasts whose IFs are usually interdispersed among microtubules. Within the large filament bundles of senescent fibroblasts, cross-bridge-like extensions are frequently observed along the individual IFs. Immunogold labeling with antibody to one of the cross-bridging proteins, p50, further illustrates the abundance of interfilament links within the IF bundles. The senescence-related increase in interfilament association was also supported by the results of co-precipitation between vimentin and an associated protein of 50,000 D. Time-lapse cinematographic studies of cell locomotion reveal that accompanying aging, fibroblasts have a significantly reduced ability to translocate across a solid substratum. These results led me to suggest that the increased interfilament links via cross-bridges may in part contribute to the mechanism that orchestrates the formation of large filament bundles. The presence of enormous bundles in the cytoplasm may physically impede the efficiency of locomotion for these nondividing cells.

Vectorial transport of proteins by membrane-bound ribosomes of nongrowing and growing Jerusalem artichoke tuber cells

1978 ◽  
Vol 56 (3) ◽  
pp. 167-173
Author(s):  
Joachim Sparkuhl ◽  
George Setterfield
Keyword(s):  
Reductase Activity ◽  
Jerusalem Artichoke ◽  
Jerusalem Artichoke Tuber ◽  
Protease Digestion ◽  
Associated Proteins ◽  
Membrane Bound ◽  
Nadh Cytochrome ◽  
Vectorial Transport

Both nongrowing (water-incubated) and growing (hormonally stimulated) Jerusalem artichoke tuber cells contain membrane-bound (mb) ribosomes. Using a rapid flotation procedure, a membrane fraction was prepared from both types of cells. This fraction was enriched in mb ribosomes, contained NADH cytochrome c reductase activity, had RNA:phospholipid and RNA:protein ratios similar to those reported for rough microsomes from animal tissues, and supported synthesis of preinitiated proteins in vitro. Using puromycin and detergent release, vectorial transport of labelled polypeptides was measured in the in vitro system. Of proteins made by mb ribosomes from nongrowing cells, only 12% remained associated with microsome membranes following chain termination. The comparable figure for proteins from mb ribosomes of growing tissue was 42%. The membrane-associated proteins were preferentially protected from protease digestion. Some possible reasons are suggested for the correlation between cell growth and the association of newly synthesized proteins with microsomes. The role of proteins synthesized by mb ribosomes but not vectorially transported, in both growing and nongrowing cells, is unknown.

Aggregation of Human Immunodeficiency Virus Type 1 by Human Salivary Secretions

1993 ◽  
Vol 4 (3) ◽  
pp. 467-474 ◽  
Author(s):  
Earl J. Bergey ◽  
Moon-Il Cho ◽  
Marie-Louise Hammarskjöld ◽  
David Rekosh ◽  
Michael J. Levine ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Inhibitory Activity ◽  
Plaque Assay ◽  
Electron Microscopic Examination ◽  
Epidemiological Data ◽  
Electron Microscopic ◽  
Two Samples ◽  
Immunodeficiency Virus ◽  
Hiv 1

Human immunodeficiency virus (HIV-1) is generally transmitted by parenteral contact with infected body secretions. Although extensive epidemiological data and familial studies have failed to provide any conclusive data that saliva may act as a vehicle for transmission of AIDS, both professional and public anxieties remain. The present study, as well as others, suggests that salivary secretions may act as inhibitors of HTV-1 replication in vitro. In our study, the inhibitory activity was determined to be associated mainly with secretions obtained from the human submandibular-sublingual glands. Human submandibular-sublingual (HSMSL) and parotid (HPS) salivas were collected and tested for their ability to modulate the replication of HIV-1, using a plaque assay on HeLa/CD4+ cell monolayers. Initial results examining freshly collected salivary samples from ten individuals confirmed the results previously obtained by Fox et al. (1988, 1989). An average plaque reduction of~66% was obtained with HSMSL, in contrast to 34% reduction obtained with HPS. Titration of the inhibitory activity in HSMSL showed detectable levels at a 1:500 dilution. Comparison of inhibitory activity of dialyzed and lyophilized saliva to fresh saliva indicated little difference between the two samples when filtration occurred after the addition of HIV-1. However, the effect of filtration was significantly diminished in the lyophilized samples. Electron microscopic examination of the saliva-HIV incubates revealed the aggregation/entrapment of virus particles by salivary components. These results suggest that human salivary secretions (with HSMSL > HPS) may have a role in modulating the infectivity of HIV-1.

scholarly journals ELECTRON MICROSCOPE STUDIES OF THE MICROVILLI OF HELA CELLS

1967 ◽  
Vol 34 (2) ◽  
pp. 569-576 ◽  
Author(s):  
Harold W. Fisher ◽  
T. W. Cooper
Keyword(s):  
Hela Cells ◽  
Electron Microscopic Examination ◽  
Spatial Arrangement ◽  
Bottom Surface ◽  
Electron Microscopic ◽  
Replica Technique ◽  
Embedding Technique ◽  
Surface Replica

Microvilli of HeLa cells cultured in vitro were preserved for electron microscopic examination at different stages of routine cultivation procedures. By a double-embedding technique, vertical sectioning for electron microscopy was possible. It revealed that, although the microvilli were present on all sides of the cell in the dispersed stage and in the attached stage, they were not present on the bottom of the cell when it was stretched on the surface of the dish. When the cells were grown in dense colonies, they were found on top of each other, and microvilli were present on all sides, except on the bottom surface of those cells in contact with the dish. We achieved a more dramatic demonstration of the microvilli by developing a surface-replica technique which retains their spatial arrangement and permits characterization of the distribution of their number, length, and diameter.

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