Toxicity testing of highly volatile chemicals with green algae

1994 ◽  
Vol 1 (4) ◽  
pp. 223-228 ◽  
Author(s):  
Werner Brack ◽  
Horst Rottler
Keyword(s):  
Green Algae ◽  
Toxicity Testing ◽  
Volatile Chemicals

Freeze-Fracture Replication in the Ultrastructure of Blue-Green Algae

1967 ◽  
Vol 25 ◽  
pp. 74-75
Author(s):  
L. V. Leak
Keyword(s):  
Cell Wall ◽  
Electron Microscope ◽  
Green Algae ◽  
Three Dimensional ◽  
Freeze Fracture ◽  
Electron Microscopic ◽  
Photosynthetic Membranes ◽  
Blue Green Algae ◽  
Cell Biol ◽  
Cellular Components

Electron microscopic observations of freeze-fracture replicas of Anabaena cells obtained by the procedures described by Bullivant and Ames (J. Cell Biol., 1966) indicate that the frozen cells are fractured in many different planes. This fracturing or cleaving along various planes allows one to gain a three dimensional relation of the cellular components as a result of such a manipulation. When replicas that are obtained by the freeze-fracture method are observed in the electron microscope, cross fractures of the cell wall and membranes that comprise the photosynthetic lamellae are apparent as demonstrated in Figures 1 & 2.A large portion of the Anabaena cell is composed of undulating layers of cytoplasm that are bounded by unit membranes that comprise the photosynthetic membranes. The adjoining layers of cytoplasm are closely apposed to each other to form the photosynthetic lamellae. Occassionally the adjacent layers of cytoplasm are separated by an interspace that may vary in widths of up to several 100 mu to form intralamellar vesicles.

A Scanning Electron Microscopic Study of Pro-Vascular Cellular Morphology in Chaetophora Incressata

1985 ◽  
Vol 43 ◽  
pp. 638-639
Author(s):  
A. E. Hotchkiss ◽  
A. T. Hotchkiss ◽  
R. P. Apkarian
Keyword(s):  
Green Algae ◽  
Vascular Plants ◽  
Vascular System ◽  
Higher Plants ◽  
Wall Structure ◽  
Electron Microscopic ◽  
Physiological Processes ◽  
Scanning Electron Microscopic Study ◽  
Scanning Electron Microscopic ◽  
Scanning Electron

Multicellular green algae may be an ancestral form of the vascular plants. These algae exhibit cell wall structure, chlorophyll pigmentation, and physiological processes similar to those of higher plants. The presence of a vascular system which provides water, minerals, and nutrients to remote tissues in higher plants was believed unnecessary for the algae. Among the green algae, the Chaetophorales are complex highly branched forms that might require some means of nutrient transport. The Chaetophorales do possess apical meristematic groups of cells that have growth orientations suggestive of stem and root positions. Branches of Chaetophora incressata were examined by the scanning electron microscope (SEM) for ultrastructural evidence of pro-vascular transport.

Toxicity testing in the development of anticancer drugs

2002 ◽  
Vol 3 (7) ◽  
pp. 440-441
Author(s):  
N Barnard
Keyword(s):  
Anticancer Drugs ◽  
Toxicity Testing

Toxicity testing in the development of anticancer drugs

2002 ◽  
Vol 3 (7) ◽  
pp. 439-440
Author(s):  
N Barrass
Keyword(s):  
Anticancer Drugs ◽  
Toxicity Testing

The Toxicity Profile of a Single Dose of Paroxetine: An Alternative Approach to Acute Toxicity Testing in the Rat

2001 ◽  
Vol 88 (2) ◽  
pp. 59-66 ◽  
Author(s):  
Pauline M. Ryan ◽  
John P. Kelly1Note ◽  
Philip L. Chambers ◽  
Brian E. Leonard
Keyword(s):  
Single Dose ◽  
Acute Toxicity ◽  
Toxicity Testing ◽  
Toxicity Profile ◽  
Alternative Approach ◽  
Acute Toxicity Testing

SPECIAL PROBLEMS IN TOXICITY TESTING OF LONG ACTING DEPOT CONTRACEPTIVES

1974 ◽  
Vol 77 (1_Suppla) ◽  
pp. S315-S354 ◽  
Author(s):  
F. Neumann ◽  
R. von Berswordt-Wallrabe ◽  
W. Elger ◽  
K.-J. Gräf ◽  
S. H. Hasan ◽  
...  
Keyword(s):  
Biological Effects ◽  
Histological Finding ◽  
Toxicity Testing ◽  
Prolactin Secretion ◽  
List Type ◽  
Human Species ◽  
Prolactin Plasma Level ◽  
Human Use ◽  
Long Acting ◽  
Reproductive Processes

ABSTRACT Two types of so-called "depot contraceptives", long-acting steroids which are of interest for human use, were studied in animals. Norethisterone oenanthate, mainly gestagenic in the human and other species, turned out to be predominantly oestrogenic in rats. This oestrogenicity caused indirectly, via an enhanced hypophysial prolactin secretion, the well-known hypophysial and mammary tumours in rats. Another synthetic gestagen, 4,6-dichloro- 17- acetoxy- 16α-methyl-4,6-pregnadiene-3,20-dione, which might be considered in its biological actions similar to preparations containing chlormadinone acetate or medroxy-progesterone acetate, induced no signs of oestrogenicity in dogs. It is surmised that its gestagenic influence indirectly, and probaby, via an enhanced hypophysial prolactin secretion caused "mammary nodules" in this "non-rodent" species. These studies have born out mainly two facts: A synthetic steroid, norethisterone oenanthate, exerted different biological effects in different species: it was a gestagen in the rabbit, whereas in rats, its predominant influence was oestrogenic. The hypophysial prolactin secretion was enhanced in various species by different mechanisms: in rats, the oestrogenicity caused an increased prolactin plasma level, whereas in dogs, a gestagen with obviously no inherent oestrogenicity, 4,6-dichloro-17-acetoxy-16α-methyl-4,6-pregnadiene-3,20-dione, converted the histological appearance of the anterior pituitary into a condition with a greatly increased number of eosinophils. This histological finding was interpreted as an indicator for a hypersecretion of prolactin. Hence, animal work with "gestagens" has only limited predictive value with respect to their possible effects in the human species. Therefore, inflexible recommendations are not helpful in solving the safety problem of long-acting steroids which affect primarily reproductive processes.

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