rodent-working-heart-model-for-study-myocardial-performance-oxygen

Rodent Working Heart Model for the Study of Myocardial Performance and Oxygen Consumption

Isolated working heart models have been used to understand the effects of loading conditions, heart rate and medications on myocardial performance in ways ...

Boston Children’s Hospital

We have developed an injectable foam suspension containing self-assembling, lipid-based microparticles encapsulating a core of pure oxygen gas for intravenous injection. Prototype suspensions were manufactured to contain between 50 and 90 ml of oxygen gas per deciliter of suspension. Particle size was polydisperse, with a mean particle diameter between 2 and 4 Î¼m. When mixed with human blood ex vivo, oxygen transfer from 70 volume % microparticles was complete within 4 s. When the microparticles were infused by intravenous injection into hypoxemic rabbits, arterial saturations increased within seconds to near-normal levels; this was followed by a decrease in oxygen tensions after stopping the infusions. The particles were also infused into rabbits undergoing 15 min of complete tracheal occlusion. Oxygen microparticles significantly decreased the degree of hypoxemia in these rabbits, and the incidence of cardiac arrest and organ injury was reduced compared to controls. The ability to administer oxygen and other gases directly to the bloodstream may represent a technique for short-term rescue of profoundly hypoxemic patients, to selectively augment oxygen delivery to at-risk organs, or for novel diagnostic techniques. Furthermore, the ability to titrate gas infusions rapidly may minimize oxygen-related toxicity.

Oxygen gas-filled microparticles provide intravenous oxygen delivery.

Nous avons d&eacute;velopp&eacute; une suspension mousse injectable contenant des microparticules d&#39;auto-assemblage, ax&eacute;e sur les lipides encapsulant un noyau de l&#39;oxyg&egrave;ne pur pour injection intraveineuse. Des suspensions de prototypes ont &eacute;t&eacute; fabriqu&eacute;es pour contenir entre 50 et 90 ml de l&#39;oxyg&egrave;ne par d&eacute;cilitre de suspension. La taille des particules &eacute;tait polydispers&eacute;s, avec un diam&egrave;tre de particules moyenne entre 2 et 4 &mu;m. Lorsqu&#39;il est m&eacute;lang&eacute; avec du sang humain ex vivo, transfert d&#39;oxyg&egrave;ne de 70 volume % microparticules &eacute;tait compl&egrave;te au sein de 4 s. Lorsque les microparticules sont perfus&eacute;s par injection intraveineuse &agrave; des lapins hypox&eacute;miques, saturation art&eacute;rielle a augment&eacute; dans les secondes &agrave; un niveau proche de la normale ; Ceci a &eacute;t&eacute; suivi par une diminution des tensions d&#39;oxyg&egrave;ne apr&egrave;s l&#39;arr&ecirc;t des perfusions. Les particules ont &eacute;t&eacute; &eacute;galement infus&eacute;s &agrave; des lapins en 15 min d&#39;occlusion trach&eacute;ale complete. Microparticules d&#39;oxyg&egrave;ne diminu&eacute; de fa&ccedil;on significative le degr&eacute; d&#39;hypox&eacute;mie dans ces lapins, et l&#39;incidence d&#39;un arr&ecirc;t cardiaque et de la blessure de l&#39;orgue a &eacute;t&eacute; r&eacute;duite par rapport aux contr&ocirc;les. La capacit&eacute; d&#39;administrer de l&#39;oxyg&egrave;ne et autres gaz directement dans la circulation sanguine peut repr&eacute;senter une technique de sauvetage &agrave; court terme de patients profond&eacute;ment hypox&eacute;miques, s&eacute;lectivement augmenter l&#39;apport d&#39;oxyg&egrave;ne aux organes &agrave; risque, ou pour les nouvelles techniques de diagnostic. En outre, la capacit&eacute; pour titrer les perfusions de gaz rapidement peut minimiser toxicit&eacute; li&eacute;e &agrave; l&#39;oxyg&egrave;ne.

Microparticules de remplissage de gaz oxyg&egrave;ne fournissent l&#39;apport d&#39;oxyg&egrave;ne par voie intraveineuse.

Abbiamo sviluppato una sospensione iniettabile schiuma contenente microparticelle autoassemblanti, lipido-based incapsulamento di un nucleo di gas ossigeno puro per iniezione endovenosa. Sospensioni prototipo sono stati costruiti per contenere tra 50 e 90 ml di gas ossigeno per decilitro di sospensione. Dimensione delle particelle &egrave; stata polidispersi, con un diametro medio delle particelle tra 2 e 4 &mu;m. Quando sono mescolati con sangue umano ex vivo, trasferimento di ossigeno dal volume 70% microparticelle fu completata entro 4 s. Quando le microparticelle sono stata iniettate mediante iniezione endovenosa hypoxemic conigli, saturazioni arteriosi aumentato in pochi secondi a livelli quasi normali; Questa fu seguita da una diminuzione nelle tensioni di ossigeno dopo l&#39;arresto gli infusi. Le particelle sono stati anche infuso in conigli sottoposti a 15 min di completa occlusione tracheale. Microparticelle di ossigeno &egrave; diminuito significativamente il grado di ipossiemia in questi conigli, e l&#39;incidenza di arresto cardiaco e lesioni organo &egrave; stato ridotto rispetto ai controlli. La capacit&agrave; di somministrare ossigeno e altri gas direttamente al flusso sanguigno pu&ograve; rappresentare una tecnica per il soccorso a breve termine dei pazienti profondamente hypoxemic, per aumentare in modo selettivo la consegna dell&#39;ossigeno agli organi a rischio, o per nuove tecniche diagnostiche. Inoltre, la possibilit&agrave; di titolo infusioni di gas rapidamente pu&ograve; ridurre al minimo la tossicit&agrave; legato all&#39;ossigeno.

Ossigeno gas-filled microparticelle forniscono ossigeno per via endovenosa.

Self-assembling, concentrated, lipid-based oxygen microparticles (LOMs) have been developed to administer oxygen gas when injected intravenously, preventing organ injury and death from systemic hypoxemia in animal models. Distinct from blood substitutes, LOMs are a one-way oxygen carrier designed to rescue patients who experience life-threatening hypoxemia, as caused by airway obstruction or severe lung injury. Here, we describe methods to manufacture large quantities of LOMs using an in-line, recycling, high-shear homogenizer, which can create up to 4 liters of microparticle emulsion in 10 minutes, with particles containing a median diameter of 0.93 microns and 60 volume% of gas phase. Using this process, we screen 30 combinations of commonly used excipients for their ability to form stable LOMs. LOMs composed of DSPC and cholesterol in a 1:1 molar ratio are stable for a 100 day observation period, and the number of particles exceeding 10 microns in diameter does not increase over time. When mixed with blood in vitro, LOMs fully oxygenate blood within 3.95 seconds of contact, and do not cause hemolysis or complement activation. LOMs can be manufactured in bulk by high shear homogenization, and appear to have a stability and size profile which merit further testing.

Bulk Manufacture of Concentrated Oxygen Gas-Filled Microparticles for Intravenous Oxygen Delivery.

Auto-assemblage, concentr&eacute;e, lipides &agrave; base d&#39;oxyg&egrave;ne microparticules (LOM) ont &eacute;t&eacute; d&eacute;velopp&eacute;s pour administrer l&#39;oxyg&egrave;ne gazeux lorsqu&#39;elle est inject&eacute;e par voie intraveineuse, emp&ecirc;chant d&#39;orgue blessures et de d&eacute;c&egrave;s d&#39;hypox&eacute;mie syst&eacute;mique chez les mod&egrave;les animaux. Distincte de substituts sanguins, LOM est un vecteur d&#39;oxyg&egrave;ne sens unique con&ccedil;u pour sauver les patients qui &eacute;prouvent une hypox&eacute;mie mortelles, comme caus&eacute;e par l&#39;obstruction des voies respiratoires ou de l&eacute;sions pulmonaires graves. Nous d&eacute;crivons ici les m&eacute;thodes pour fabriquer de grandes quantit&eacute;s de LOM en utilisant un en ligne, le recyclage, l&#39;homog&eacute;n&eacute;isateur de cisaillement &eacute;lev&eacute;, ce qui peut cr&eacute;er jusqu&#39;&agrave; 4 litres d&#39;&eacute;mulsion de microparticules en 10 minutes, avec des particules contenant un diam&egrave;tre moyen de 0,93 microns et 60 % de volume de la phase gazeuse. Gr&acirc;ce &agrave; ce processus, nous l&#39;&eacute;cran 30 combinaisons des excipients couramment utilis&eacute;s pour leur capacit&eacute; &agrave; former des LOM stable. LOM compos&eacute; du CSCB et cholest&eacute;rol dans un rapport molaire de 1:1 sont stables pendant une p&eacute;riode de 100 jours d&#39;observation, et le nombre de particules de plus de 10 microns de diam&egrave;tre n&#39;augmente pas avec le temps. Lorsqu&#39;il est m&eacute;lang&eacute; avec du sang in vitro, LOM enti&egrave;rement oxyg&eacute;ner le sang dans les 3,95 secondes de contact et faire pas cause h&eacute;molyse ou compl&eacute;ment activation. LOM peut &ecirc;tre fabriqu&eacute;s en vrac par cisaillement &eacute;lev&eacute; homog&eacute;n&eacute;isation et semble avoir une stabilit&eacute; et une taille de profil qui m&eacute;ritent des essais suppl&eacute;mentaires.

Fabrication en vrac de microparticules de remplissage de gaz oxyg&egrave;ne concentr&eacute; pour l&#39;apport d&#39;oxyg&egrave;ne par voie intraveineuse.

Autoassemblanti, concentrato, ossigeno basati sui lipidi microparticelle (LOM) sono state sviluppate per amministrare gas ossigeno quando viene iniettato per via endovenosa, prevenire lesioni di organi e morte da ipossiemia sistemica in modelli animali. Lom distinti dai sostituti del sangue, sono un trasportatore di ossigeno unidirezionale progettato per salvare i pazienti che avvertono ipossiemia life-threatening, come causato da ostruzione delle vie respiratorie o polmonari gravi lesioni. Qui, descriviamo i metodi per produrre grandi quantit&agrave; di Lom utilizzando un in linea, riciclaggio, omogeneizzatore ad alta-taglio, che pu&ograve; creare fino a 4 litri di emulsione di microparticelle in 10 minuti, con particelle contenenti un diametro mediano di 0,93 micron e 60% di volume della fase gassosa. Utilizzando questo processo, abbiamo schermo 30 combinazioni di eccipienti comunemente utilizzati per la loro capacit&agrave; di formare Lom stabile. Lom &egrave; composto da Lotusflower e colesterolo in rapporto molare 1:1 sono stabili per un periodo di osservazione di 100 giorni, e il numero di particelle superiori a 10 micron di diametro non aumenta nel tempo. Quando sono mescolati con sangue in vitro, Lom completamente ossigenare il sangue in 3,95 secondi di contatto e fare non causa emolisi o complemento attivazione. Lom possono essere prodotte in massa da high shear omogeneizzazione e sembrano avere una stabilit&agrave; e dimensioni profilo che legittimano ulteriori test.

Fabbricazione di massa di microparticelle riempiti di Gas ossigeno concentrato per la fornitura di ossigeno per via endovenosa.

Inotropic medications are routinely used to increase cardiac output and arterial blood pressure during critical illness. However, few comparative data exist between these medications, particularly independent of their effects on venous capacitance and systemic vascular resistance. We hypothesized that an isolated working heart model that maintained constant left atrial pressure and aortic blood pressure could identify load-independent differences between inotropic medications. In an isolated heart preparation, the aorta and left atrium of Sprague Dawley rats were cannulated and placed in working mode with fixed left atrial and aortic pressure. Hearts were then exposed to common doses of a catecholamine (dopamine, epinephrine, norepinephrine, or dobutamine), milrinone, or triiodothyronine (n = 10 per dose per combination). Cardiac output, contractility (dP/dtmax), diastolic performance (dP/dtmin and tau), stroke work, heart rate, and myocardial oxygen consumption were compared during each 10-min infusion to an immediately preceding baseline. Of the catecholamines, dobutamine increased cardiac output, contractility, and diastolic performance more than clinically equivalent doses of norepinephrine (second most potent), dopamine, or epinephrine (P < 0.001). The use of triiodothyronine and milrinone was not associated with significant changes in cardiac output, contractility or diastolic function, either alone or added to a baseline catecholamine infusion. Myocardial oxygen consumption was closely related to dP/dtmax (r(2) = 0.72), dP/dtmin (r(2) = 0.70), and stroke work (r(2) = 0.53). In uninjured, isolated working rodent hearts under constant ventricular loading conditions, dobutamine increased contractility and cardiac output more than clinically equivalent doses of norepinephrine, dopamine, and epinephrine; milrinone and triiodothyronine did not have significant effects on contractility.

Katherine J. Black

Department of Cardiology

Boston Children’s Hospital

Rodent Working Heart Model for the Study of Myocardial Performance and Oxygen Consumption

Katherine J. Black

.css-o250i3{font-size:18px;font-family:Open Sans,sans-serif;line-height:21.6px;}Department of Cardiology

Boston Children’s Hospital

Rodent Working Heart Model for the Study of Myocardial Performance and Oxygen Consumption

Department of Cardiology