Flexible intravenous microdialysis probe for blood sampling in freely moving rats

1993 ◽  
Vol 74 (1) ◽  
pp. 466-469 ◽  
Author(s):  
P. Rada ◽  
M. Parada ◽  
L. Hernandez
Keyword(s):  
Blood Sampling ◽  
In Vitro Tests ◽  
Microdialysis Probe ◽  
Freely Moving Rats ◽  
Intravenous Microdialysis ◽  
Silastic Tubing ◽  
Freely Moving ◽  
Circulating Levels

A flexible intravenous microdialysis probe was constructed from Silastic tubing (0.5 mm ID and 1.0 mm OD), with a cellulose hollow fiber tip 0.2 mm in diameter and 25 mm long with a 6,000 mol wt cut off. In vitro tests showed relative recovery rates of 39.1 +/- 1.9% for epinephrine. In vivo tests in freely moving rats, 36 h and 7 days after surgery, showed stable amounts of epinephrine and glucose. After intraperitoneal injections of 2-deoxy-D-glucose, circulating levels of epinephrine and glucose increased significantly. Similar results were obtained several days after implantation of the probe. We conclude that in situations where prolonged blood sampling is necessary, the flexible microdialysis probe provides a reliable means of accessing circulating levels of neuroactive compounds, nutrients, metabolites, and drugs.

scholarly journals Orexin A suppresses in vivo GH secretion

2004 ◽  
pp. 731-736 ◽  
Author(s):  
LM Seoane ◽  
SA Tovar ◽  
D Perez ◽  
F Mallo ◽  
M Lopez ◽  
...  
Keyword(s):  
Nutritional Status ◽  
Area Under The Curve ◽  
Sleep Regulation ◽  
Gh Secretion ◽  
Neuroendocrine Function ◽  
Freely Moving Rats ◽  
Freely Moving ◽  
The Brain

BACKGROUND/AIMS: Orexins (OXs) are a newly described family of hypothalamic neuropeptides. Based on the distribution of OX neurons and their receptors in the brain, it has been postulated that they could play a role in the regulation of neuroendocrine function. GH secretion is markedly influenced by nutritional status and body weight. To investigate the role OX-A plays in the neuroregulation of GH secretion we have studied its effect on spontaneous GH secretion as well as GH responses to GHRH and ghrelin in freely moving rats. Finally, we also assessed the effect of OX-A on in vitro GH secretion. METHODS: We administered OX-A (10 microg, i.c.v.) or vehicle (10 microl, i.c.v.) to freely moving rats. Spontaneous GH secretion was assessed over 6 h with blood samples taken every 15 min. RESULTS: Administration of OX-A led to a decrease in spontaneous GH secretion in comparison with vehicle-treated rats, as assessed by mean GH levels (means+/-s.e.m. 4.2+/-1.7 ng/ml vs 9.4+/-2.2 ng/ml; P<0.05), mean GH amplitude (3.6+/-0.5 ng/ml vs 20.8+/-5.6 ng/ml; P<0.01) and area under the curve (848+/-379 ng/ml per 4 h vs 1957+/-458 ng/ml per 4 h; P<0.05). In contrast, OX-A failed to modify in vivo GH responses to GHRH (10 microg/kg, i.v.) although it markedly blunted GH responses to ghrelin (40 microg/kg, i.v.) (mean peak GH levels: 331+/-71 ng/ml, vehicle, vs 43+/-11 ng/ml in OX-A-treated rats; P<0.01). Finally, OX-A infusion (10(-7), 10(-8) or 10(-9) M) failed to modify in vitro basal GH secretion or GH responses to GHRH, ghrelin and KCl. CONCLUSIONS: These data indicate that OX-A plays an inhibitory role in GH secretion and may act as a bridge among the regulatory signals that are involved in the control of growth, nutritional status and sleep regulation.

Honokiol and Magnolol Increased Hippocampal Acetylcholine Release in Freely-Moving Rats

2000 ◽  
Vol 28 (03n04) ◽  
pp. 379-384 ◽  
Author(s):  
Yu-Chi Hou ◽  
Pei-Dawn Lee Chao ◽  
Shiouh-Yi Chen
Keyword(s):  
Acetylcholine Release ◽  
Stem Bark ◽  
High Dose ◽  
M 10 ◽  
Freely Moving Rats ◽  
Freely Moving ◽  
Magnolia Officinalis ◽  
Choline Acetyltransferase Activity

Honokiol and magnolol, phenolic compounds isolated from the stem bark of Magnolia officinalis, have been demonstrated to increase choline acetyltransferase activity, inhibit acetylcholinesterase, promote potassium-induced acetylcholine release and exhibit neurotrophic function in in vitro studies. The objective of the present study was to determine the effect of these compounds on hippocampal acetylcholine release in conscious, freely-moving rats. 10-4 M–10-6 M of honokiol or magnolol was perfused into rat hippocampus via a dialysis probe. The results showed that at 10-4 M concentration, honokiol and magnolol markedly increased extracellular acetylcholine release to 165.5 ± 5.78% and 237.83 ± 9.47% of the basal level, respectively. However, lower concentrations of either compounds failed to elicit significant acetylcholine release. This result suggests that a high dose of honokiol or magnolol may enhance in vivo hippocampal acetylcholine release.

scholarly journals Ghrelin elicits a marked stimulatory effect on GH secretion in freely-moving rats

2000 ◽  
pp. R7-R9 ◽  
Author(s):  
LM Seoane ◽  
S Tovar ◽  
R Baldelli ◽  
E Arvat ◽  
E Ghigo ◽  
...  
Keyword(s):  
Physiological Control ◽  
Gh Secretion ◽  
Freely Moving Rats ◽  
Anaesthetized Rats ◽  
Freely Moving ◽  
The One ◽  
Plasma Gh ◽  
Different Doses

Ghrelin is a growth hormone-releasing acylated peptide from stomach. The purified peptide consist of 28 amino acids in which the serine 3 residue is n-octanoylated. Ghrelin has been reported to increase in vitro GH secretion as well as in vivo plasma GH levels in pentobarbital anaesthetized rats. The aim of this work was to characterize the stimulatory effect of Ghrelin on in vivo GH secretion in freely-moving rats. Furthermore, we compare the effect of Ghrelin with GHRH. In addition to vehicle, we administered different doses of Ghrelin (3 nmol/Kg, 12 nmol/Kg and 60 nmol/Kg); GHRH (3 nmol/Kg and 12 nmol/kg). Plasma GH levels were measured in blood samples taken at 5, 10, 15, 20, 30 and 45 min after their administration as an i.v. bolus at 0 min. Administration of Ghrelin led to an increase in plasma GH levels at all time-points tested (5, 10, 15, 20 and 30 min, P<0.01; and 45 min, P<0.05) in comparison to control untreated rats. A maximal stimulatory effect on plasma GH was observed following administration of 12 nmol/Kg of Ghrelin, the effect being similar to the one obtained with 60 nmol/Kg in terms of both AUC and mean peak GH levels. At the dose of 3 nmol/Kg GHRH and Ghrelin exhibited a similar stimulatory effect in term of both, AUC and mean peak GH levels. However following administration of a dose of 12 nmol/Kg, the effect of Ghrelin was much greater than the same dose of GHRH in terms of both AUC and mean peak GH levels. In summary, this study provides the first evidences that Ghrelin exert a marked stimulatory effect in plasma GH levels in freely-moving rats and provides further evidences that Ghrelin may play an important role in the physiological control of GH secretion.

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.

A Comparison of the in Vitro and in Vivo Thrombogenic Activity of Factor IX Concentrates Using Stasis (Wessler) and Non-Stasis Rabbit Models

1980 ◽  
Vol 44 (02) ◽  
pp. 081-086 ◽  
Author(s):  
C V Prowse ◽  
A E Williams
Keyword(s):  
Platelet Rich Plasma ◽  
Thrombus Formation ◽  
Factor Ix ◽  
Coagulation System ◽  
In Vitro Tests ◽  
Clinical Use ◽  
Low Activity

SummaryThe thrombogenic effects of selected factor IX concentrates were evaluated in two rabbit models; the Wessler stasis model and a novel non-stasis model. Concentrates active in either the NAPTT or TGt50 in vitro tests of potential thrombogenicity, or both, caused thrombus formation in the Wessler technique and activation of the coagulation system in the non-stasis model. A concentrate with low activity in both in vitro tests did not have thrombogenic effects in vivo, at the chosen dose. Results in the non-stasis model suggested that the thrombogenic effects of factor IX concentrates may occur by at least two mechanisms. A concentrate prepared from platelet-rich plasma and a pyrogenic concentrate were also tested and found to have no thrombogenic effect in vivo.These studies justify the use of the NAPTT and TGt50 in vitro tests for the screening of factor IX concentrates prior to clinical use.

Inhibition of Fibrinolysis and Fibrinogenolysis in Man: Comparison of ε-Aminocaproic Acid and Kallikrein Inhibitor

1963 ◽  
Vol 10 (01) ◽  
pp. 106-119 ◽  
Author(s):  
E Beck ◽  
R Schmutzler ◽  
F Duckert ◽  
Keyword(s):  
Aminocaproic Acid ◽  
Side Reactions ◽  
In Vitro Tests ◽  
Factor V ◽  
Clinical Use ◽  
Strong Inhibitor ◽  
Kallikrein Inhibitor ◽  
Therapeutic Possibilities

SummaryInhibitor of kallikrein and trypsin (KI) extracted from bovine parotis was compared with ε-aminocaproic acid (EACA): both substances inhibit fibrinolysis induced with streptokinase. EACA is a strong inhibitor of fibrinolysis in concentrations higher than 0, 1 mg per ml plasma. The same amount and higher concentrations are not able to inhibit completely the proteolytic-side reactions of fibrinolysis (fibrinogenolysis, diminution of factor V, rise of fibrin-polymerization-inhibitors). KI inhibits well proteolysis of plasma components in concentrations higher than 2,5 units per ml plasma. Much higher amounts of KI are needed to inhibit fibrinolysis as demonstrated by our in vivo and in vitro tests.Combination of the two substances for clinical use is suggested. Therapeutic possibilities are discussed.

Role of in vivo and in vitro Tests in the Diagnosis of Severe Cutaneous Adverse Reactions (SCAR) to Drug

2019 ◽  
Vol 25 (36) ◽  
pp. 3872-3880 ◽  
Author(s):  
Marcel M. Bergmann ◽  
Jean-Christoph Caubet
Keyword(s):  
Adverse Reactions ◽  
Lymphocyte Transformation ◽  
Stevens Johnson Syndrome ◽  
In Vitro Tests ◽  
High Morbidity ◽  
Patch Tests ◽  
Severe Cutaneous Adverse Reactions ◽  
Cutaneous Adverse Reactions

Severe cutaneous adverse reactions (SCAR) are life-threatening conditions including acute generalized exanthematous pustulosis (AGEP), Stevens-Johnson Syndrome (SJS), toxic epidermal necrolysis (TEN) and drug reaction with eosinophilia and systemic symptoms (DRESS). Diagnosis of causative underlying drug hypersensitivity (DH) is mandatory due to the high morbidity and mortality upon re-exposure with the incriminated drug. If an underlying DH is suspected, in vivo test, including patch tests (PTs), delayed-reading intradermal tests (IDTs) and in vitro tests can be performed in selected patients for which the suspected culprit drug is mandatory, or in order to find a safe alternative treatment. Positivity of in vivo and in vitro tests in SCAR to drug varies depending on the type of reaction and the incriminated drugs. Due to the severe nature of these reactions, drug provocation test (DPT) is highly contraindicated in patients who experienced SCAR. Thus, sensitivity is based on positive test results in patients with a suggestive clinical history. Patch tests still remain the first-line diagnostic tests in the majority of patients with SCAR, followed, in case of negative results, by delayed-reading IDTs, with the exception of patients with bullous diseases where IDTs are still contra-indicated. In vitro tests have shown promising results in the diagnosis of SCAR to drug. Positivity is particularly high when the lymphocyte transformation test (LTT) is combined with cytokines and cytotoxic markers measurement (cyto-LTT), but this still has to be confirmed with larger studies. Due to the rarity of SCAR, large multi-center collaborative studies are needed to better study the sensitivity and specificity of in vivo and in vitro tests.

Methylprednisolone on circulating eicosanoids and vasomotor tone after endotoxin

1986 ◽  
Vol 61 (1) ◽  
pp. 185-191 ◽  
Author(s):  
C. A. Hales ◽  
R. D. Brandstetter ◽  
C. F. Neely ◽  
M. B. Peterson ◽  
D. Kong ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Vascular Resistance ◽  
Systemic Blood Pressure ◽  
Physiological Effect ◽  
High Dose ◽  
Systemic Blood ◽  
Eicosanoid Production ◽  
Circulating Levels

Acute pulmonary and systemic vasomotor changes induced by endotoxin in dogs have been related, at least in part, to the production of eicosanoids such as the vasoconstrictor thromboxane and the vasodilator prostacyclin. Steroids in high doses, in vitro, inhibit activation of phospholipase A2 and prevent fatty acid release from cell membranes to enter the arachidonic acid cascade. We, therefore, administered methylprednisolone (40 mg/kg) to dogs to see if eicosanoid production and the ensuing vasomotor changes could be prevented after administration of 150 micrograms/kg of endotoxin. The stable metabolites of thromboxane B2 (TxB2) and 6-ketoprostaglandin F1 alpha (6-keto-PGF1 alpha) were measured by radioimmunoassay. Methylprednisolone by itself did not alter circulating eicosanoids but when given 2.5 h before endotoxin not only failed to inhibit endotoxin-induced eicosanoid production but actually resulted in higher circulating levels of 6-keto-PGF1 alpha (P less than 0.05) compared with animals receiving endotoxin alone. Indomethacin prevented the steroid-enhanced concentrations of 6-keto-PGF1 alpha after endotoxin and prevented the greater fall (P less than 0.05) in systemic blood pressure and systemic vascular resistance with steroid plus endotoxin than occurred with endotoxin alone. Administration of methylprednisolone immediately before endotoxin resulted in enhanced levels (P less than 0.05) of both TxB2 and 6-keto-PGF1 alpha but with a fall in systemic blood pressure and vascular resistance similar to the animals pretreated by 2.5 h. In contrast to the early steroid group in which all of the hypotensive effect was due to eicosanoids, in the latter group steroids had an additional nonspecific effect. Thus, in vivo, high-dose steroids did not prevent endotoxin-induced increases in eicosanoids but actually increased circulating levels of TxB2 and 6-keto-PGF1 alpha with a physiological effect favoring vasodilation.

Hemostatic wound dressings: Predicting their effects by in vitro tests

2019 ◽  
Vol 33 (9) ◽  
pp. 1285-1297 ◽  
Author(s):  
Cornelia Wiegand ◽  
Martin Abel ◽  
Uta-Christina Hipler ◽  
Peter Elsner ◽  
Michael Zieger ◽  
...  
Keyword(s):  
Blood Clot ◽  
Wound Dressings ◽  
In Vitro Tests ◽  
Regenerated Cellulose ◽  
Oxidized Regenerated Cellulose ◽  
Inflammatory Reactions ◽  
In Vitro Techniques ◽  
Cotton Gauze

Background Application of controlled in vitro techniques can be used as a screening tool for the development of new hemostatic agents allowing quantitative assessment of overall hemostatic potential. Materials and methods Several tests were selected to evaluate the efficacy of cotton gauze, collagen, and oxidized regenerated cellulose for enhancing blood clotting, coagulation, and platelet activation. Results Visual inspection of dressings after blood contact proved the formation of blood clots. Scanning electron microscopy demonstrated the adsorption of blood cells and plasma proteins. Significantly enhanced blood clot formation was observed for collagen together with β-thromboglobulin increase and platelet count reduction. Oxidized regenerated cellulose demonstrated slower clotting rates not yielding any thrombin generation; yet, led to significantly increased thrombin-anti-thrombin-III complex levels compared to the other dressings. As hemostyptica ought to function without triggering any adverse events, induction of hemolysis, instigation of inflammatory reactions, and initiation of the innate complement system were also tested. Here, cotton gauze provoked high PMN elastase and elevated SC5b-9 concentrations. Conclusions A range of tests for desired and undesired effects of materials need to be combined to gain some degree of predictability of the in vivo situation. Collagen-based dressings demonstrated the highest hemostyptic properties with lowest adverse reactions whereas gauze did not induce high coagulation activation but rather activated leukocytes and complement.

scholarly journals In vivo assessment of a single adenine mutation in 5′UTR of Endothelin-1 gene in paediatric cases with severe pulmonary hypertension: an observational study

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Abhishek Kumar ◽  
Minati Choudhury ◽  
Sakshi Dhingra Batra ◽  
Kriti Sikri ◽  
Anushree Gupta
Keyword(s):  
Pulmonary Hypertension ◽  
Congenital Heart ◽  
Small Sample Size ◽  
Small Sample ◽  
Severe Pulmonary Hypertension ◽  
Endothelin 1 ◽  
Circulating Levels ◽  
In Vivo Assessment

Abstract Objective Endothelin-1 plays an important role in the pathogenesis of severe pulmonary hypertension. The + 139 ‘A’, adenine insertion variant in 5′UTR of edn1 gene has been reported to be associated with increased expression of Endothelin-1 in vitro. The aim of present study was to explore the association of this variant with the circulating levels of Endothelin-1 in vivo using archived DNA and plasma samples from 38 paediatric congenital heart disease (cyanotic and acyanotic) patients with severe pulmonary hypertension. Results The plasma Endothelin-1 levels were highly varied ranging from 1.63 to75.16 pg/ml. The + 139 ‘A’ insertion variant in 5′UTR of edn1 was seen in 8 out of 38 cases with only one acyanotic sample demonstrating homozygosity of inserted ‘A’ allele at + 139 site (4A/4A genotype). The plasma Endothelin-1 levels in children with homozygous variant 3A/3A genotype were comparable in cyanotic and acyanotic groups. Lone 4A/4A acyanotic sample had ET-1 levels similar to the median value of ET-1 associated with 3A/3A genotype and was absent in cyanotic group presumably due to deleterious higher ET-1 levels. The discussed observations, limited by the small sample size, are suggestive of homozygous adenine insertion variant posing a risk in cyanotic babies with Severe Pulmonary Hypertension.

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