Vitamin A Metabolism is Altered in Brown Norway and Long-Evans Rats Infused with Naftidrofuryl or Erythromycin Intravenously

2002 ◽  
Vol 72 (4) ◽  
pp. 210-220 ◽  
Author(s):  
Rainer Schindler ◽  
Tanja Fielenbach ◽  
Gerhard Rave ◽  
Anne Blömer ◽  
Richard Kellersmann
Keyword(s):  
Vitamin A ◽  
Time Course ◽  
Drug Exposure ◽  
Drug Loading ◽  
Interactive Effect ◽  
Brown Norway ◽  
Retinyl Ester ◽  
Vitamin A Metabolism ◽  
Long Evans

Enzymatic retinyl ester hydrolysis is a key reaction for maintaining cellular retinol homeostasis. The ability of naftidrofuryl and erythromycin to inhibit retinol liberation by retinyl ester hydrolase (REH) in vitro suggests an ability to interfere with vitamin A metabolism in vivo, particularly during hepatic processing. To address this question, systemic and local response to these agents were studied in Brown Norway (BN) and Long-Evans (LE) rats. The study was conducted in two parts: a drug-loading phase and a washout phase. Analysis of variance of the time course changes in plasma retinol during the post-treatment period (Days 10–18) showed rat strain (p < 0.04) and time (p < 0.001; strain-by-time interactive effect, p < 0.001) to be significant factors, but drug exposure (p = 0.19) was not significant. Endpoints included hepatic REH activity, size and composition of the liver vitamin A stores, and retinoid content of the kidneys. Rats recovering from naftidrofuryl dosing demonstrated a lower REH activity than did animals recovering from erythromycin treatment (p < 0.009). The major side effect of erythromycin is vitamin A accumulation in the liver (p < 0.001) and reductions in retinol reserves (p < 0.02) were among the consequences of naftidrofuryl treatment. In the kidney of LE rats, there were higher concentrations of vitamin A (p < 0.003) secondary to naftidrofuryl exposure. Together our data suggest that clinically achievable concentrations of the drugs, given as a continuous infusion, produce aberrations in vitamin A metabolism.

scholarly journals Flupenthixol and cefotiam: effects on vitamin A metabolism in rats

2004 ◽  
Vol 92 (4) ◽  
pp. 597-605 ◽  
Author(s):  
Rainer Schindler ◽  
Tanja Fielenbach ◽  
Gerhard Rave
Keyword(s):  
Vitamin A ◽  
Retinol Binding Protein ◽  
Brown Norway ◽  
Early Event ◽  
Retinyl Ester ◽  
Vitamin A Metabolism ◽  
Ester Hydrolase ◽  
Retinyl Ester Hydrolase ◽  
Plasma Retinol ◽  
The Impact

We examined the alterations in vitamin A metabolism as a result of flupenthixol or cefotiam administration. The impact of these drugs on indices of vitamin A status was evaluated in Brown Norway and Long–Evans rats. Intramuscular drug administration for 28 d resulted in a decline in systemic retinol. Changes in circulating retinol with time for chronic dosing showed drug treatment (P<0·001) and time (P<0·03) to be significant factors, but rat strain (P=0·33) was not a significant factor. Flupenthixol was the most active retinol-lowering compound (P<0·005). At the end of the 28 d period, hepatic retinyl ester hydrolase activity was greater in drug-treated rats than in controls (P<0·05). With regard to effects on liver reserves: (1) flupenthixol treatment resulted in vitamin A depletion (P<0·05); (2) cefotiam treatment stimulated vitamin A accumulation; (3) distinctive patterns of retinol and its esters were seen in response to treatment. It is reasonable to assume that the drugs interfere with vitamin A in at least two ways: (1) lowering of plasma retinol, an early event in the interaction, may be caused by inhibition of hepatic holo-retinol-binding protein secretion or stimulation of clearance, or both; (2) when plasma retinol levels are persistently low, and as the hepatic deposits of the xenobiotics build up, there are changes in the vitamin A pool size and composition of the liver. Candidate enzymes are retinyl ester hydrolase and cytochrome P450. The relationship between these two events will be studied in further detail.

scholarly journals A comparative study on the effects of oral amiodarone and trimeprazine, two in vitro retinyl ester hydrolase inhibitors, on the metabolic availability of vitamin A in rats

2005 ◽  
Vol 94 (5) ◽  
pp. 675-683 ◽  
Author(s):  
Rainer Schindler ◽  
Tanja Fielenbach ◽  
Gerhard Rave
Keyword(s):  
Vitamin A ◽  
Tolerance Test ◽  
Brown Norway ◽  
Oral Drug ◽  
Retinyl Ester ◽  
Ester Hydrolase ◽  
Retinyl Ester Hydrolase ◽  
Pre Treatment ◽  
Plasma Retinol

Amiodarone, an antiarrhythmic drug, and trimeprazine, an antipsychotic drug, are both in vitro inhibitors of retinyl ester hydrolase. To determine whether these agents have deleterious effects on aspects of vitamin A metabolism, Brown Norway rats (n 18) were treated at clinically equivalent doses once daily for 26d with either oral drug. On day 27, a tolerance test was used to determine whether these agents interfered with vitamin absorption. During the first 8d, the plasma retinol level declined in all animals. Between days 12 and 27, it rose to near pre-treatment concentrations in the control and trimeprazine groups and remained relatively constant at low levels (P<0·001) in the amiodarone group. The intestinal absorption of vitamin A was reduced (P<0·05) in the amiodarone group compared with the placebo and trimeprazine groups, which did not differ significantly from each other. At the end of the 4-week treatment period, hepatic retinyl ester hydrolase activity was lower in the drug-dosed rats (P=0·06 for amiodarone) than in the controls. With regard to effects on liver reserves, drug treatment resulted in vitamin A depletion (P<0·019), and distinctive patterns of retinol and its esters were seen in response to dosing. In conclusion, amiodarone and trimeprazine have been shown to influence different aspects of retinoid metabolism, namely absorption, storage and transport. In clinical practice, the routine unmonitored use of these drugs and the suggestion that these agents be taken with meals are not recommended.

scholarly journals Pharmacokinetic/Pharmacodynamic (PK/PD) Indices of Antibiotics Predicted by a Semimechanistic PKPD Model: a Step toward Model-Based Dose Optimization

2011 ◽  
Vol 55 (10) ◽  
pp. 4619-4630 ◽  
Author(s):  
Elisabet I. Nielsen ◽  
Otto Cars ◽  
Lena E. Friberg
Keyword(s):  
Drug Concentration ◽  
Time Course ◽  
Drug Exposure ◽  
Full Time ◽  
Antibacterial Drugs ◽  
Model Based ◽  
Pkpd Model ◽  
Dosing Intervals ◽  
Time Kill

ABSTRACTA pharmacokinetic-pharmacodynamic (PKPD) model that characterizes the full time course ofin vitrotime-kill curve experiments of antibacterial drugs was here evaluated in its capacity to predict the previously determined PK/PD indices. Six drugs (benzylpenicillin, cefuroxime, erythromycin, gentamicin, moxifloxacin, and vancomycin), representing a broad selection of mechanisms of action and PK and PD characteristics, were investigated. For each drug, a dose fractionation study was simulated, using a wide range of total daily doses given as intermittent doses (dosing intervals of 4, 8, 12, or 24 h) or as a constant drug exposure. The time course of the drug concentration (PK model) as well as the bacterial response to drug exposure (in vitroPKPD model) was predicted. Nonlinear least-squares regression analyses determined the PK/PD index (the maximal unbound drug concentration [fCmax]/MIC, the area under the unbound drug concentration-time curve [fAUC]/MIC, or the percentage of a 24-h time period that the unbound drug concentration exceeds the MIC [fT>MIC]) that was most predictive of the effect. Thein silicopredictions based on thein vitroPKPD model identified the previously determined PK/PD indices, withfT>MICbeing the best predictor of the effect for β-lactams andfAUC/MIC being the best predictor for the four remaining evaluated drugs. The selection and magnitude of the PK/PD index were, however, shown to be sensitive to differences in PK in subpopulations, uncertainty in MICs, and investigated dosing intervals. In comparison with the use of the PK/PD indices, a model-based approach, where the full time course of effect can be predicted, has a lower sensitivity to study design and allows for PK differences in subpopulations to be considered directly. This study supports the use of PKPD models built fromin vitrotime-kill curves in the development of optimal dosing regimens for antibacterial drugs.

Chick Rearing III. The effect of diet on vitamin A, xanthophyll and carotene metabolism

1945 ◽  
Vol 35 (2) ◽  
pp. 101-107 ◽  
Author(s):  
T. Barton Mann
Keyword(s):  
Vitamin A ◽  
Fish Meal ◽  
Vitamin A Metabolism ◽  
Meat Meal ◽  
Basal Ration

Evidence is presented, based on feeding tests, that vitamin A metabolism is adversely affected when meat meal having a vitamin A consuming power in vitro is included in the diet of chicks.Evidence is presented, based on feeding tests, that when fish meal having no vitamin A consuming power in vitro is fed to chicks in a basal ration which produces negligible mortality, the addition of such fish meal to the ration does not appreciably increase mortality.Evidence is presented, based on feeding tests, that when fish meal having a vitamin A consuming power in vitro is fed to chicks in a basal ration which produces negligible mortality, the addition of such fish meal to the ration causes appreciable mortality.

Vitamin A metabolism: α-Tocopherol modulates tissue retinol levels in vivo, and retinyl palmitate hydrolysis in vitro

1984 ◽  
Vol 230 (1) ◽  
pp. 194-202 ◽  
Author(s):  
Joseph L. Napoli ◽  
Anne M. McCormick ◽  
Brian O'Meara ◽  
Edward A. Dratz
Keyword(s):  
Vitamin A ◽  
Retinyl Palmitate ◽  
Vitamin A Metabolism

scholarly journals Altered Expression of Genes Involved in Regulation of Vitamin A Metabolism, Solute Transportation, and Cytoskeletal Function in the Androgen-Insensitive Tfm Mouse Testis

Endocrinology ◽  
2007 ◽  
Vol 148 (6) ◽  
pp. 2914-2924 ◽  
Author(s):  
P. J. O’Shaughnessy ◽  
M. Abel ◽  
H. M. Charlton ◽  
B. Hu ◽  
H. Johnston ◽  
...  
Keyword(s):  
Vitamin A ◽  
Real Time ◽  
Real Time Pcr ◽  
Developmental Study ◽  
Altered Expression ◽  
Vitamin A Metabolism ◽  
Expression Of Genes ◽  
Cytoskeletal Function ◽  
Underlying Mechanisms

Androgens are essential for the development and maintenance of spermatogenesis, but the underlying mechanisms of androgen action in the testis remain unclear. To help clarify these mechanisms, gene expression was measured in testes of pubertal (20 d old), androgen-insensitive, testicular feminized (Tfm) mice and in normal controls. Using microarrays (Affymetrix chips 430A and 430B), initial data identified a large number of genes down-regulated in the Tfm testis (&gt;4700). These genes were largely of germ cell origin, reflecting the arrest of spermatogenesis that is apparent in the 20-d-old Tfm testis. Subsequent screening in vitro and in silico of this gene set identified 20 genes of a somatic tubular origin that were significantly down-regulated in the Tfm testis and six genes that were significantly up-regulated. Altered expression of these genes was confirmed by real-time PCR, and genes down-regulated in the Tfm testis were shown to be up-regulated in testes of hypogonadal (hpg) mice treated with androgen. In a developmental study using real-time PCR most of the regulated genes showed normal expression during fetal and neonatal development and deviated from control only between 10 and 20 d. In all cases, expression was also reduced in the adult, although interpretation is more complex because of the inherent cryptorchidism in the adult Tfm mouse. Of the total number of somatic genes showing differential expression in the Tfm testis, 50% were associated with three separate groups of genes involved in regulation of vitamin A metabolism, solute transportation, and cytoskeletal function. Thus, effects of androgens on tubular function and spermatogenesis may be mediated in part through regulation of the tubular environment and control of retinoic acid concentrations.

An in vitro model for investigation of vitamin A effects on wound healing

2021 ◽  
pp. 1-6
Author(s):  
Hoda Keshmiri Neghab ◽  
Mohammad Hasan Soheilifar ◽  
Gholamreza Esmaeeli Djavid
Keyword(s):  
Wound Healing ◽  
Endothelial Cell ◽  
Vitamin A ◽  
In Vitro Model ◽  
Cellular Proliferation ◽  
Endothelial Cell Migration ◽  
Normal Fibroblast ◽  
Anti Inflammatory ◽  
Vitro Model

Abstract. Wound healing consists of a series of highly orderly overlapping processes characterized by hemostasis, inflammation, proliferation, and remodeling. Prolongation or interruption in each phase can lead to delayed wound healing or a non-healing chronic wound. Vitamin A is a crucial nutrient that is most beneficial for the health of the skin. The present study was undertaken to determine the effect of vitamin A on regeneration, angiogenesis, and inflammation characteristics in an in vitro model system during wound healing. For this purpose, mouse skin normal fibroblast (L929), human umbilical vein endothelial cell (HUVEC), and monocyte/macrophage-like cell line (RAW 264.7) were considered to evaluate proliferation, angiogenesis, and anti-inflammatory responses, respectively. Vitamin A (0.1–5 μM) increased cellular proliferation of L929 and HUVEC (p < 0.05). Similarly, it stimulated angiogenesis by promoting endothelial cell migration up to approximately 4 fold and interestingly tube formation up to 8.5 fold (p < 0.01). Furthermore, vitamin A treatment was shown to decrease the level of nitric oxide production in a dose-dependent effect (p < 0.05), exhibiting the anti-inflammatory property of vitamin A in accelerating wound healing. These results may reveal the therapeutic potential of vitamin A in diabetic wound healing by stimulating regeneration, angiogenesis, and anti-inflammation responses.

Comparison of High Purity Factor IX Concentrates and a Prothrombin Complex Concentrate in a Canine Model of Thrombogenicity

1991 ◽  
Vol 66 (05) ◽  
pp. 609-613 ◽  
Author(s):  
I R MacGregor ◽  
J M Ferguson ◽  
L F McLaughlin ◽  
T Burnouf ◽  
C V Prowse
Keyword(s):  
High Purity ◽  
Time Course ◽  
Prothrombin Complex Concentrate ◽  
Degradation Products ◽  
Canine Model ◽  
Factor Ix ◽  
In Vitro Tests ◽  
Albumin Infusion

SummaryA non-stasis canine model of thrombogenicity has been used to evaluate batches of high purity factor IX concentrates from 4 manufacturers and a conventional prothrombin complex concentrate (PCC). Platelets, activated partial thromboplastin time (APTT), fibrinogen, fibrin(ogen) degradation products and fibrinopeptide A (FPA) were monitored before and after infusion of concentrate. Changes in FPA were found to be the most sensitive and reproducible indicator of thrombogenicity after infusion of batches of the PCC at doses of between 60 and 180 IU/kg, with a dose related delayed increase in FPA occurring. Total FPA generated after 100-120 IU/kg of 3 batches of PCC over the 3 h time course was 9-12 times that generated after albumin infusion. In contrast the amounts of FPA generated after 200 IU/kg of the 4 high purity factor IX products were in all cases similar to albumin infusion. It was noted that some batches of high purity concentrates had short NAPTTs indicating that current in vitro tests for potential thrombogenicity may be misleading in predicting the effects of these concentrates in vivo.

The Effect of Heparin vs. Citrate on the Interaction of Platelets with Vascular Graft Materials

1985 ◽  
Vol 54 (04) ◽  
pp. 842-848 ◽  
Author(s):  
Kandice Kottke-Marchant ◽  
James M Anderson ◽  
Albert Rabinovitch ◽  
Richard A Huskey ◽  
Roger Herzig
Keyword(s):  
Platelet Aggregation ◽  
Platelet Activation ◽  
Vascular Graft ◽  
Time Course ◽  
Platelet Reactivity ◽  
Polymer Surfaces ◽  
In Vitro Perfusion ◽  
Citrate Anticoagulation ◽  
Platelet Release

SummaryHeparin is known to affect platelet function in vitro, but little is known about the effect of heparin on the interaction of platelets with polymer surfaces in general, and vascular graft materials in particular. For this reason, the effect of heparin vs. citrate anticoagulation on the interaction of platelets with the vascular graft materials expanded polytetrafluoroethylene (ePTFE), Dacron Bionit (DB) and preclotted Dacron Bionit (DB/PC) was studied in a recirculating, in vitro perfusion system. Platelet activation, as shown by a decrease in platelet count, an increase in platelet release and a decrease in platelet aggregation, was observed for all vascular graft materials tested using heparin and was greater for Dacron and preclotted Dacron than for ePTFE. Significant differences between heparin and citrate anticoagulation were seen for platelet release, platelet aggregation and the relative ranking of material platelet-reactivity. However, the trends and time course of platelet activation were similar with both heparin and citrate for the materials tested.

Preparation and in vitro Evaluation of Bioadhesive Microparticulate System

1970 ◽  
Vol 1 (3) ◽  
pp. 257-266
Author(s):  
Nagda C. D. ◽  
Chotai N. P. ◽  
Patel S. B. ◽  
Soni T. J ◽  
Patel U. L
Keyword(s):  
Drug Loading ◽  
In Vitro Release ◽  
Phenyl Acetic Acid ◽  
Solvent Evaporation Method ◽  
Elimination Half ◽  
Release Studies ◽  
Differential Scanning Colorimetry ◽  
Polymer Interactions ◽  
Vitro Release

Aceclofenac (ACE) is NSAIDs of a phenyl acetic acid class. It is indicated in arthritis and osteoarthritis, rheumatoid arthritis, ankylosing spondylitis. It has short elimination half life of 4 hours. The objective of the study is to design, characterize and evaluate bioadhesive microspheres of ACE employing carbopol (CP) as bioadhesive polymer. Bioadhesive microspheres of ACE were prepared by solvent evaporation method. The prepared microspheres were free flowing and spherical in shape and characterized for drug loading, mucoadhesion test, infrared spectroscopy (IR), differential scanning colorimetry (DSC) and scanning electron microscopy (SEM). The in-vitro release studies were performed using pH 6.8 phosphate buffer. The drug loaded microspheres in a ratio of 1:5 showed 47% of drug entrapment; percentage mucoadhesion was 81% and 89% release in 10 h. The infrared spectra and DSC showed stable character of aceclofenac in the drug loaded microspheres and revealed the absence of drug-polymer interactions. SEM studies showed that the microspheres are spherical and porous in nature. The in vitro release profiles from microspheres of different polymer-drug ratios followed Higuchi model.

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