scholarly journals Metabolic hydroxylations of trans-stilbene

1969 ◽  
Vol 111 (1) ◽  
pp. 35-41 ◽  
Author(s):  
J. E. Sinsheimer ◽  
R. V. Smith
Keyword(s):  
Guinea Pig ◽  
Liver Microsomes ◽  
Rabbit Liver ◽  
Microsomal Enzyme ◽  
Hydroxylase Activity ◽  
Microsomal Preparation ◽  
Trans Stilbene ◽  
Enzyme Isolation ◽  
Liver Microsomal Preparation

1. A study was made of the hydroxylation of trans-stilbene in rabbits, guinea pigs and mice, as well as by rabbit liver microsomes. 2. In the rabbit in vivo, trans-stilbene is converted into 4-hydroxy-,4,4′-dihydroxy-,3-hydroxy-4-methoxy-and 4-hydroxy-3-methoxy-stilbene, and hydroxylation plays a more significant role in the metabolism of trans-stilbene than has previously been reported. 3. Investigation of the hydroxylation of 4-hydroxystilbene in the rabbit in vivo demonstrated its ready conversion into 4,4′-dihydroxystilbene and established its intermediacy in the formation of this compound and the methylated analogues of 3,4-dihydroxystilbene. 4. Hydroxylation of trans-stilbene in the guinea pig was found to follow a pattern similar, both qualitatively and quantitatively, to that in the rabbit. 5. Studies in the mouse revealed only limited yields of 4,4′-dihydroxystilbene. 6. Studies of the hydroxylation of trans-stilbene and 4-hydroxystilbene by rabbit liver microsomes located two of the reactions that occur with these compounds in vivo. 7. Work with a solubilized liver-microsomal preparation provided evidence that ‘stilbene hydroxylase’ activity is not completely lost on solubilization, thus allowing for future microsomal enzyme-isolation studies.

Enzymic Cleavage Of In Vivo Formed Maillard-Type Compounds Involved In Haemostasis

1981 ◽  
Author(s):  
L Mester ◽  
L Szabados ◽  
M Mester
Keyword(s):  
Enzyme System ◽  
Basal Membrane ◽  
Enzyme Concentration ◽  
Cytochrome P450 Enzyme ◽  
Microsomal Preparation ◽  
Chemical Hydrolysis ◽  
P450 Enzyme ◽  
Liver Microsomal Preparation

Desoxyfructose derivatives of serotonin (Mester et al.,1975), of haemoglobin (Flückiger and Winterhalter, 1976), of poly-L-lysine (Mester et al., 1975) and of lysine rich histones (Kertesz-Crisba, 1977) are easily formed in vivo by a simple Maillard-type chemical reaction. Some of these compounds interfere with platelet functions (Mester et al.,1976) or contribute to the thickening of the basal membrane of blood vessels (Cerami et al., 1979).While the chemical synthesis of Maillard-type compounds proceeds readily even in vivo, the chemical cleavage of them needs sever conditions which certainly do not exist in vivo (Gottschalk, 1952). However, a slow liberation of serotonin from desoxyfructo-serotonin is observed in vivo, suggesting the existence of an enzyme system for the cleavage of Maillard-type sugar-amine derivatives. In vitro, using a sheep liver microsomal preparation rich in Cytochrome P450 enzyme, the liberation of serotonin is in linear correlation with the enzyme concentration. The cleavage of desoxyfructo-serotonin is activated by NADPH having its optimum at pH=7.4, excluding definitely the occurence of a chemical hydrolysis.Factors interfering with the enzyme system involved in the cleavage of Maillard-type compounds, may also interfere with haemostasis.

scholarly journals Metabolism of 11-oxygenated steroids. Metabolism in vitro by preparations of liver

1968 ◽  
Vol 107 (2) ◽  
pp. 239-258 ◽  
Author(s):  
I. E. Bush ◽  
Sheila A. Hunter ◽  
R. A. Meigs
Keyword(s):  
Guinea Pig ◽  
Dehydrogenase Activity ◽  
Liver Microsomes ◽  
Competitive Inhibitor ◽  
Partial Purification ◽  
Substrate Complex ◽  
Hydroxy Steroid ◽  
Steroid Dehydrogenase

1. The isolation and partial purification of 11β-hydroxy steroid dehydrogenase from rat and guinea-pig liver microsomes has been achieved by conventional methods. 2. The efficiency of different 11-oxygenated steroids as substrates has been examined. The relative efficiencies confirm in the main the stereochemical theory of the enzyme–coenzyme–substrate complex that was proposed earlier on the basis of studies in vivo. Δ4-3-Ketones and 5α-hydrogen steroids are readily metabolized by the enzyme. 5β-Hydrogen steroids and Δ4-3-ketones with certain large α-substituents are metabolized to a limited extent or not at all. Halogen substitution in the 9α-position enhances the rate of reduction of 11-ketones but blocks the oxidation of the related 11β-ols. 3. 9α-Fluorocortisol is a competitive inhibitor of the oxidation of cortisol, but 9α-fluorocortisone is reduced at five to ten times the initial velocity of cortisone. 4. 11β-Hydroxy steroid dehydrogenase activity has been found in liver microsomes of rat, guinea pig, rabbit and calf. 5. Relative substrate efficiencies and Km values are similar in whole (debris-free) homogenates, washed microsomes and acetone-dried powders of washed microsomes. 6. A variety of conditions have been examined for the observation of 11β-hydroxy steroid dehydrogenase activity. NADP(H) is an efficient and NAD(H) a very poor coenzyme for the reaction.

Inhibition of Human and Animal Platelet Adhesiveness to Glass Bead Columns by Adenosine, Dipyridamole, Chlorpromazine and Acetylsalicylic Acid

1976 ◽  
Vol 36 (02) ◽  
pp. 401-410 ◽  
Author(s):  
Buichi Fujttani ◽  
Toshimichi Tsuboi ◽  
Kazuko Takeno ◽  
Kouichi Yoshida ◽  
Masanao Shimizu
Keyword(s):  
Guinea Pig ◽  
Acetylsalicylic Acid ◽  
Guinea Pigs ◽  
Glass Bead ◽  
Animal Species ◽  
Inhibitory Effect ◽  
Rabbit Platelet ◽  
Platelet Adhesiveness

SummaryThe differences among human, rabbit and guinea-pig platelet adhesiveness as for inhibitions by adenosine, dipyridamole, chlorpromazine and acetylsalicylic acid are described, and the influence of measurement conditions on platelet adhesiveness is also reported. Platelet adhesiveness of human and animal species decreased with an increase of heparin concentrations and an increase of flow rate of blood passing through a glass bead column. Human and rabbit platelet adhesiveness was inhibited in vitro by adenosine, dipyridamole and chlorpromazine, but not by acetylsalicylic acid. On the other hand, guinea-pig platelet adhesiveness was inhibited by the four drugs including acetylsalicylic acid. In in vivo study, adenosine, dipyridamole and chlorpromazine inhibited platelet adhesiveness in rabbits and guinea-pigs. Acetylsalicylic acid showed the inhibitory effect in guinea-pigs, but not in rabbits.

In vivo activity of pyrimidine-dispirotripiperaziniumin in the male guinea pig model of genital herpes

2020 ◽  
Vol 09 (01) ◽  
Author(s):  
Novoselova EA ◽  
Alimbarova LM ◽  
Monakhova NS ◽  
Lepioshkin AY ◽  
Ekins S ◽  
...  
Keyword(s):  
Guinea Pig ◽  
Genital Herpes ◽  
Pig Model ◽  
Guinea Pig Model

scholarly journals Optimization of spectral-domain optical coherence tomography with a supercontinuum source for in vivo motion detection of low reflective outer hair cells in guinea pig cochleae

2021 ◽  
Author(s):  
Fumiaki Nin ◽  
Samuel Choi ◽  
Takeru Ota ◽  
Zhang Qi ◽  
Hiroshi Hibino
Keyword(s):  
Optical Coherence Tomography ◽  
High Resolution ◽  
Guinea Pig ◽  
Hair Cells ◽  
Sensory Epithelium ◽  
Outer Hair Cells ◽  
Acquisition Time ◽  
Total Acquisition Time ◽  
Sd Oct

AbstractSound evokes sub-nanoscale vibration within the sensory epithelium. The epithelium contains not only immotile cells but also contractile outer hair cells (OHCs) that actively shrink and elongate synchronously with the sound. However, the in vivo motion of OHCs has remained undetermined. The aim of this work is to perform high-resolution and -accuracy vibrometry in live guinea pigs with an SC-introduced spectral-domain optical coherence tomography system (SD-OCT). In this study, to reveal the effective contribution of SC source in the recording of the low reflective materials with the short total acquisition time, we compare the performances of the SC-introduced SD-OCT (SCSD-OCT) to that of the conventional SD-OCT. As inanimate comparison objects, we record a mirror, a piezo actuator, and glass windows. For the measurements in biological materials, we use in/ex vivo guinea pig cochleae. Our study achieved the optimization of a SD-OCT system for high-resolution in vivo vibrometry in the cochlear sensory epithelium, termed the organ of Corti, in mammalian cochlea. By introducing a supercontinuum (SC) light source and reducing the total acquisition time, we improve the axial resolution and overcome the difficulty in recording the low reflective material in the presence of biological noise. The high power of the SC source enables the system to achieve a spatial resolution of 1.72 ± 0.00 μm on a mirror and reducing the total acquisition time contributes to the high spatial accuracy of sub-nanoscale vibrometry. Our findings reveal the vibrations at the apical/basal region of OHCs and the extracellular matrix, basilar membrane.

scholarly journals Specificity in the activation and inhibition by flavonoids of benzo[a]pyrene hydroxylation by cytochrome P-450 isozymes from rabbit liver microsomes.

1981 ◽  
Vol 256 (21) ◽  
pp. 10897-10901 ◽  
Author(s):  
M.T. Huang ◽  
E.F. Johnson ◽  
U. Muller-Eberhard ◽  
D.R. Koop ◽  
M.J. Coon ◽  
...  
Keyword(s):  
Liver Microsomes ◽  
Rabbit Liver ◽  
Cytochrome P 450
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