scholarly journals Blood Retention and Antigenicity of Polycarboxybetaine-Modified Liposomes

2020 ◽  
Author(s):  
Taka-aki Ryujin ◽  
Taro Shimizu ◽  
Ryo Miyahara ◽  
Rena Shimazui ◽  
Takuma Yoshikawa ◽  
...  
Keyword(s):  
Immunological Tolerance ◽  
Liposomal Formulation ◽  
Pegylated Liposome ◽  
Protein Conjugates ◽  
High Doses ◽  
Dose Dependent ◽  
Non Fouling

<div>Zwitterionic polycarboxybetaines (PCBs) have gained attention as alternative stealth polymers whose</div><div>liposomal formulation and protein conjugates were reported not to elicit anti-polymer antibodies. Here, we</div><div>studied the blood retention and antigenicity of liposomes modified with PCBs focusing on their chemical</div><div>structures and doses. We compared PCBs with either 1 or 3 (PCB1 or PCB3) spacer carbons between the</div><div>carboxylate and ammonium groups. PCB3-modified liposomes had a short blood retention, whereas PCB1-</div><div>modified liposomes demonstrated extended blood retention that was somewhat superior to PEGylated liposome.</div><div>This confirmed the excellent non-fouling nature of PCB1 reported previously. Interestingly, PCB1-liposome as</div><div>well as PCB3-liposome elicited specific IgMs toward each PCB. The dose-dependent production of specific</div><div>IgMs to PCB-liposomes was similar to that of PEGylated liposome, i.e., high doses of PCB-liposomes reduced</div><div>the production of specific IgMs, termed immunological tolerance. These results indicate the importance of</div><div>investigating the effect of dose to clarify the existence of antigenicity of stealth polymers</div>

scholarly journals Blood Retention and Antigenicity of Polycarboxybetaine-Modified Liposomes

2020 ◽  
Author(s):  
Taka-aki Ryujin ◽  
Taro Shimizu ◽  
Ryo Miyahara ◽  
Rena Shimazui ◽  
Takuma Yoshikawa ◽  
...  
Keyword(s):  
Immunological Tolerance ◽  
Liposomal Formulation ◽  
Pegylated Liposome ◽  
Protein Conjugates ◽  
High Doses ◽  
Dose Dependent ◽  
Non Fouling

<div>Zwitterionic polycarboxybetaines (PCBs) have gained attention as alternative stealth polymers whose</div><div>liposomal formulation and protein conjugates were reported not to elicit anti-polymer antibodies. Here, we</div><div>studied the blood retention and antigenicity of liposomes modified with PCBs focusing on their chemical</div><div>structures and doses. We compared PCBs with either 1 or 3 (PCB1 or PCB3) spacer carbons between the</div><div>carboxylate and ammonium groups. PCB3-modified liposomes had a short blood retention, whereas PCB1-</div><div>modified liposomes demonstrated extended blood retention that was somewhat superior to PEGylated liposome.</div><div>This confirmed the excellent non-fouling nature of PCB1 reported previously. Interestingly, PCB1-liposome as</div><div>well as PCB3-liposome elicited specific IgMs toward each PCB. The dose-dependent production of specific</div><div>IgMs to PCB-liposomes was similar to that of PEGylated liposome, i.e., high doses of PCB-liposomes reduced</div><div>the production of specific IgMs, termed immunological tolerance. These results indicate the importance of</div><div>investigating the effect of dose to clarify the existence of antigenicity of stealth polymers</div>

Melatonin actions in the heart; more than a hormone

2018 ◽  
Vol 1 (1) ◽  
pp. 21-26 ◽  
Author(s):  
Darío Acuña-Castroviejo ◽  
Maria T Noguiera-Navarro ◽  
Russel J Reiter ◽  
Germaine Escames
Keyword(s):  
Cell Membranes ◽  
Myocardial Cell ◽  
Rat Tissues ◽  
Dependent Manner ◽  
Broad Distribution ◽  
Multiple Organs ◽  
High Doses ◽  
Extrapineal Melatonin ◽  
Dose Dependent ◽  
Different Doses

Due to the broad distribution of extrapineal melatonin in multiple organs and tissues, we analyzed the presence and subcellular distribution of the indoleamine in the heart of rats. Groups of sham-operated and pinealectomized rats were sacrificed at different times along the day, and the melatonin content in myocardial cell membranes, cytosol, nuclei and mitochondria, were measured. Other groups of control animals were treated with different doses of melatonin to monitor its intracellular distribution. The results show that melatonin levels in the cell membrane, cytosol, nucleus, and mitochondria vary along the day, without showing a circadian rhythm. Pinealectomized animals trend to show higher values than sham-operated rats. Exogenous administration of melatonin yields its accumulation in a dose-dependent manner in all subcellular compartments analyzed, with maximal concentrations found in cell membranes at doses of 200 mg/kg bw melatonin. Interestingly, at dose of 40 mg/kg b.w, maximal concentration of melatonin was reached in the nucleus and mitochondrion. The results confirm previous data in other rat tissues including liver and brain, and support that melatonin is not uniformly distributed in the cell, whereas high doses of melatonin may be required for therapeutic purposes.

EFFECT OF INTRAVENTRICULAR ADMINISTRATION OF NORADRENALINE ON WATER DIURESIS IN GOATS

1975 ◽  
Vol 66 (3) ◽  
pp. 375-383 ◽  
Author(s):  
G. VANDEPUTTE-VAN MESSOM ◽  
G. PEETERS
Keyword(s):  
Intraventricular Administration ◽  
Excretion Ratio ◽  
Dose Response Relationship ◽  
Water Diuresis ◽  
3Rd Ventricle ◽  
Dependent Inhibition ◽  
Dose Dependent Inhibition ◽  
High Doses ◽  
Excretion Rates ◽  
Dose Dependent

SUMMARY During water diuresis in conscious goats, noradrenaline (NA), its antagonists phentolamine, phenoxybenzamine and propranolol and also atropine were administered into the 3rd ventricle. The subsequent effects on water diuresis and on the excretion rates of Na+, K+ and Cl− were investigated. Infusion of NA into the 3rd ventricle induced a strong and significant antidiuretic response and a decrease in the Na+: K+ excretion ratio; these effects were dose-dependent. High doses of NA produced a significant increase in urinary K+ excretion. Similar results were observed after i.v. administration of arginine-vasopressin. Pretreatment with phentolamine injected into the 3rd ventricle produced a dose-dependent inhibition of the NA-induced antidiuretic effects. Phenoxybenzamine also blocked the response to NA but a dose-response relationship was not apparent. Atropine and propranolol did not block the response to NA.

Retinoic acid application to chick wing buds leads to a dose-dependent reorganization of the apical ectodermal ridge that is mediated by the mesenchyme

Development ◽  
1989 ◽  
Vol 106 (4) ◽  
pp. 691-705 ◽  
Author(s):  
C. Tickle ◽  
A. Crawley ◽  
J. Farrar
Keyword(s):  
Retinoic Acid ◽  
Gap Junctions ◽  
Time Course ◽  
Apical Ectodermal Ridge ◽  
Threshold Response ◽  
Epithelial Morphology ◽  
Early Effects ◽  
High Doses ◽  
Columnar Cells ◽  
Dose Dependent

Local application of retinoic acid to wing buds of chick embryos leads to dose- and position-dependent changes in the pattern of cellular differentiation. Early effects of retinoid treatment on the apical ectodermal ridge coordinate pattern changes and morphogenesis. The length of the apical ridge increases when additional digits will form but decreases when digits are lost. These changes in length can be understood in terms of a threshold response to the local retinoid concentration that results in either disappearance or maintenance of the ridge (Lee & Tickle, J. Embryol. exp. Morph. 90, 139–169 (1985)). Here, we have analysed the mechanisms involved in ridge disappearance by locally applying retinoic acid to the apex of stage 20 chick wing buds. With this treatment regime, low doses give duplicated digit patterns and higher doses truncations. The height of the apical ridge is progressively reduced with increasing doses of retinoid and the time course of ridge flattening indicates that the height of the ridge is correlated with bud outgrowth. With high doses of retinoic acid, the typical ridge, a pseudostratified epithelium in which the columnar cells are tightly packed, disappears and the epithelium at the tip of the bud consists of loosely packed cuboidal cells. Shortly after treatment, there is a decrease in the number of gap junctions between ridge cells. This early change in cell contacts suggests that gap junctions may be involved in maintaining epithelial morphology. When treated epithelium is recombined with untreated mesenchyme, an apical ridge is reestablished and distal structures can be generated. In contrast, when treated mesenchyme is recombined with the epithelium from normal buds, only proximal structures are formed. Therefore, retinoids can lead to a reorganization of the apical ectodermal ridge which is mediated and maintained by the mesenchyme.

Intracerebroventricular injection of prostaglandin E2 increases splenic sympathetic nerve activity in rats

1995 ◽  
Vol 269 (3) ◽  
pp. R662-R668 ◽  
Author(s):  
T. Ando ◽  
T. Ichijo ◽  
T. Katafuchi ◽  
T. Hori
Keyword(s):  
Prostaglandin E2 ◽  
Sympathetic Nerve ◽  
Time Course ◽  
Sympathetic Nerve Activity ◽  
Dependent Manner ◽  
Central Administration ◽  
Nerve Activity ◽  
High Doses ◽  
Alpha Chloralose ◽  
Dose Dependent

The effects of central administration of prostaglandin E2 (PGE2) and its selective agonists on splenic sympathetic nerve activity (SNA) were investigated in urethan- and alpha-chloralose-anesthetized rats. An intra-third-cerebroventricular (13V) injection of PGE2 (0.1-10 nmol/kg) increased splenic SNA in a dose-dependent manner. An I3V injection of an EP1 agonist, 17-phenyl-omega-trinor PGE2 (1-30 nmol/kg), also resulted in a dose-dependent increase in splenic SNA, with a time course similar to that of PGE2-induced responses. In contrast, EP2 agonists, butaprost (10-100 nmol/kg I3V) and 11-deoxy-PGE1 (10-100 nmol/kg I3V), had no effect on splenic SNA. An I3V injection of M & B-28767 (an EP3/EP1 agonist, EP3 >> EP1) increased splenic SNA only at high doses (10-100 nmol/kg). Pretreatment with an EP1 antagonist, SC-19220 (200 and 500 nmol/kg), completely blocked the responses of splenic SNA to PGE2 (0.1 nmol/kg) and M & B-28767 (10 nmol/kg), respectively. These findings indicate that brain PGE2 increases splenic SNA through its action on EP1 receptors.

Mice lacking neuronal nicotinic acetylcholine receptor β4-subunit and mice lacking both α5- and β4-subunits are highly resistant to nicotine-induced seizures

2004 ◽  
Vol 17 (2) ◽  
pp. 221-229 ◽  
Author(s):  
Merav Kedmi ◽  
Arthur L. Beaudet ◽  
Avi Orr-Urtreger
Keyword(s):  
Nicotinic Acetylcholine Receptors ◽  
Acetylcholine Receptors ◽  
Mutant Mice ◽  
Wild Type ◽  
Nicotinic Acetylcholine ◽  
Nocturnal Frontal Lobe Epilepsy ◽  
Wide Range ◽  
High Doses ◽  
Dose Dependent ◽  
Rate Of Response

Nicotine, the main addictive component of tobacco, evokes a wide range of dose-dependent behaviors in rodents, and when administrated in high doses, it can induce clonic-tonic seizures. Nicotine acts through the nicotinic acetylcholine receptors (nAChRs). Mutations in the human α4- and the β2-nAChR subunit genes cause autosomal dominant nocturnal frontal lobe epilepsy. Using transgenic mice with mutations in nAChR subunits, it was demonstrated previously that the α4-, α5-, and α7-subunits are involved in nicotine-induced seizures. To examine the possibility that the β4-subunit is also involved in this phenotype, we tested mice with homozygous β4-subunit deficiency. The β4 null mice were remarkably resistant to nicotine-induced seizures compared with wild-type and α5 null mice. We also generated mice with double deficiency of both α5- and β4-nAChR subunits and demonstrated that they were more resistant to nicotine’s convulsant effect than either the α5 or the β4 single mutant mice. In addition, the single α5 mutants and the double α5β4-deficient mice exhibited a significantly shorter latency time to seizure than that of the wild-type mice. Our results thus show that β4-containing nAChRs have a crucial role in the pathogenesis of nicotine-induced seizures. Furthermore, by comparing multiple mutant mice with single and double subunit deficiency, we suggest that nicotinic receptors containing either α5- or β4-subunits are involved in nicotine-induced seizures and that receptors containing both subunits are likely to contribute to this phenomena as well. However, the α5-subunit, but not the β4-subunit, regulates the rate of response to high doses of nicotine.

scholarly journals Place of piracetam in the modern practice of medicine

2017 ◽  
Vol 15 (1) ◽  
pp. 14-25 ◽  
Author(s):  
Victor V Vostrikov
Keyword(s):  
Clinical Medicine ◽  
Evidence Based ◽  
Clinical Effects ◽  
Practical Application ◽  
Main Attention ◽  
Dependent Relation ◽  
Practice Of Medicine ◽  
High Doses ◽  
Based Medicine ◽  
Dose Dependent

The review considers the stages of experimental and clinical study of piracetam in the framework of evidence-based medicine, its wide practical application in various fields of clinical medicine. The main attention pays to the mechanisms of action of the drug, its properties and physiological effects. The specific dose-dependent relation is revealed for the clinical effects of piracetam: the efficiency grows higher dependent on high doses and prolongation of courses.

scholarly journals A Three-Way Drug Discrimination Study: A Role for DA-Mediated Effects in MDMA's Discriminative Cue Properties

2021 ◽  
Author(s):  
◽  
Anna-Lena Langen
Keyword(s):  
Drug Discrimination ◽  
Abuse Potential ◽  
Low Doses ◽  
Training Dose ◽  
Mediated Effects ◽  
D2 Antagonist ◽  
High Doses ◽  
Discriminative Cue ◽  
Dose Dependent ◽  
Da Release

<p>While 3,4-methylenedioxymethamphetamine (MDMA) shares many similarities with amphetamine, previous two choice drug discrimination procedures have shown that substitution between the two substances is inconsistent. Three choice drug discrimination procedures have revealed that MDMA can be discriminated from amphetamine, due to MDMA’s primary influence in releasing 5-HT. Neurochemical evidence had previously suggested that at doses >3.0mg/kg MDMA-induced dopamine (DA) release will increase significantly. In the current study rats were trained to discriminate MDMA from amphetamine and saline. As the dose of MDMA increased beyond the training dose (>1.5mg/kg) MDMA-appropriate responding decreased, while the proportion of amphetamine lever responding increased and eventually surpassed MDMA-appropriate responding at the highest dose (4.5mg/kg). This would indicate an important role for DA mediated influences in MDMA’s discriminative cue properties. Further evidence for this conclusion comes from tests with the D1 antagonist SCH23390 and the D2 antagonist eticlopride which attenuated this effect and also led to a nonsignificant increase in the proportion of saline lever responding. Subsequent tests with the 5-HT2c antagonist RS102221resulted in no significant dose dependent changes, but appeared to reduce MDMA-appropriate responding especially at the training dose. The current findings would suggest that low doses of MDMA are discriminable from amphetamine, however with increasing doses MDMA will be perceived as more “amphetamine-like”. These findings could suggest that at relatively high doses MDMA produces effects that are typically associated with dopamine-releasing drugs, such as high abuse potential.</p>

scholarly journals Birthweight Depression in Male Rats Contiguous to Male Siblings in Utero Exposed to High Doses of 1,3-Butanediol during Organogenesis

1986 ◽  
Vol 5 (4) ◽  
pp. 189-196 ◽  
Author(s):  
R. F. Mankes ◽  
V. Renak ◽  
J. Fieseher ◽  
R. Lefevre
Keyword(s):  
Developmental Toxicity ◽  
In Utero ◽  
Cellular Damage ◽  
Male Rats ◽  
Body Weights ◽  
Fetal Repair ◽  
Dose Dependent Decrease ◽  
High Doses ◽  
Embryotoxic Effects ◽  
Dose Dependent

The embryotoxic effects of high doses of the narcotizing ethanol dimer 1,3-butanediol were evaluated in pregnant Long-Evans rats during the “critical period” of organogenesis. Butanediol was given by gavage at levels of 0,7060,4236, or 706 mg/kg per day (24,14.4, or 2.4% of the acute oral LD50 value for rats). Maternal sedation was observed at 7060 and 4236 mg/kg, but feed consumptions and maternal body weights were unaffected. Butanediol caused a significant, dose-dependent decrease in offspring birthweights. At the highest butanediol dose, birthweights were preferentially and significantly decreased in male pups not contiguous in utero to female siblings. Other group I1 offspring were not affected and did not differ significantly from controls. As butanediol was given prior to the period of greatest fetal growth and fetal sex steroidogenests, it is concluded that intra-uterine levels of female sex steroids (estradiol) enhance fetal repair of cellular damage (restitution ad integrum), whereas testosterone inhibits fetal repair or exacerbates previous embryonic damage by some unknown mechanism. Such interaction furthers the concept that intrauterine position affects the endpoints of developmental toxicity, as expressed at partuition.

A model of beta-adrenergic effects on calcium and potassium current in bullfrog atrial myocytes

1991 ◽  
Vol 261 (6) ◽  
pp. H1937-H1944
Author(s):  
J. M. Shumaker ◽  
J. W. Clark ◽  
W. R. Giles
Keyword(s):  
Action Potential ◽  
Potassium Current ◽  
Beta Adrenergic ◽  
Calcium Dependent ◽  
Dependent Inactivation ◽  
Atrial Myocyte ◽  
Muscarinic Cholinergic ◽  
High Doses ◽  
Dose Dependent ◽  
Cholinergic Effects

A model of beta-adrenergic and muscarinic cholinergic effects on the bullfrog atrial myocyte has been developed to simulate the dose-dependent effects of isoprenaline (Iso) on the action potential duration (APD); i.e., low doses of Iso lengthen the APD, whereas high doses shorten the APD. In this model, the reduction in APD is the result of 1) calcium-dependent inactivation of calcium current (ICa) resulting from the enhancement of ICa by Iso and 2) an enhancement of potassium current (IK) due to both an Iso-induced increase in the rate of activation of IK and an increase in peak action potential height. The effect of acetylcholine (ACh) is simulated by a reduction in the Iso-induced increase in ICa and IK through a reduction in relative adenosine 3',5'-cyclic monophosphate concentration ([cAMP]), as well as activation of the ACh-sensitive potassium current. At low [Iso] levels in the presence of a high [ACh], the muscarinic cholinergic effects dominate the beta-adrenergic change. However, for a large [Iso] and a small [ACh], this pattern of changes in transmembrane currents is different; in this case the model predicts that ACh can actually increase APD.

Sign in / Sign up

Export Citation Format

Share Document