Potential role of the Virchow Robin space in the pathogenesis of bacterial meningitis.

Meningitis is an infectious disease commonly arising from a bacterial etiology. The rapid progression of morbidity and mortality due to bacterial meningitis requires critical and imminent time-dependent clinical intervention. Although it is unambiguously clear that bacteria must infiltrate the cerebrospinal fluid, the sequence of events in the pathogenesis of bacterial meningitis has not been fully elucidated.

Reduction in myocardial infarct size at 48 hours after brief intravenous infusion of ATL-146e, a highly selective adenosine A2A receptor agonist.

This study was undertaken to determine whether the myocardial infarct-sparing effect of ATL-146e, a selective adenosine A(2A) receptor agonist, persists without a rebound effect for at least 48 h and to determine the optimal duration of ATL-146e treatment in anesthetized dogs. Reperfusion injury after myocardial infarction (MI) is associated with inflammation lasting 24-48 h that contributes to ongoing myocyte injury. We previously showed that an ATL-146e infusion, starting just before reperfusion, decreased inflammation and infarct size in dogs examined 2 h after MI without increasing coronary blood flow.

A mechanism of vasodilatory action of polyamines and acetylpolyamines: possible involvement of their Ca2+ antagonistic properties.

Polyamines, a class of low-molecular weight organic polycations, have been shown to produce relaxing effects in vascular smooth muscles, although the mechanism has not been carefully examined. In this study, the mechanism of vascular action of polyamines and their metabolites, acetylpolyamines, was pharmacologically examined in the rabbit isolated thoracic aorta focusing on an endothelium-dependent component of vasodilatation and Ca2+ influx through plasma membrane channels. Both polyamines and acetylpolyamines (except N1-acetylputrescine, which produced no response or very slight contraction) caused concentration-dependent relaxation in preconstricted aortic rings containing an intact endothelium.

Transcapillary exchange of indium 111-labeled anticardiac myosin Fab and thallium 201 in isolated reperfused rabbit hearts.

Background: The physiologic mechanisms of 111In-labeled anticardiac myosin antibody [111In]-AM) imaging are fairly well established. However, to better understand the transcapillary exchange characteristics of normal and reperfused myocardium, a standard first-pass, indicator-dilution analysis was undertaken in hearts subjected to global no-flow and low-flow ischemia.

Methods And Results: The first-pass myocardial transport of 201Tl and [111In]-AM was evaluated in an in vitro rabbit model of no-flow ischemia/reperfusion with indicator-dilution analysis during normal and ischemic flows and whole-blood perfusate.

Myocardial extraction of technetium-99m-[2-(1-methoxybutyl) isonitrile] in the isolated rabbit heart: a myocardial perfusion agent with high extraction and stable retention.

Technetium-99m-[2-(1-methoxybutyl) isonitrile] (MBI) is a potential new compound for the scintigraphic imaging of coronary flow. Evaluation in the blood-perfused isolated rabbit heart model showed this compound to have a myocardial uptake comparable to 201Tl and higher than sestamibi. Although the mean +/- s.

Experimental studies of the physiologic properties of technetium-99m agents: myocardial transport of perfusion imaging agents.

The physiologic properties of new technetium-99m-labeled myocardial imaging agents (Tc-99m sestamibi, an isonitrile; and Tc-99m teboroxime, a boronic acid adduct of technetium dioxime) are discussed and compared to thallium-201 (Tl-201). Studies with isolated hearts, subcellular fractions and cell cultures indicate that Tc-99m sestamibi, Tc-99m teboroxime and Tl-201 do not share common transport or sequestration mechanisms. Although peak Tc-99m sestamibi myocardial extraction over time is about half that of Tl-201 at equivalent coronary blood flows, the amount of Tc-99m sestamibi that remains in the heart is similar to that of Tl-201 because of its higher retention efficiency.

Myocardial transport of hexakis(2-methoxyisobutylisonitrile) and thallium before and after coronary reperfusion.

Effects of no-flow ischemia (NFI) and reperfusion (RPF) on myocardial extraction and retention of technetium-99m hexakis(2-methoxyisobutylisonitrile) (sestamibi) and thallium-201 were investigated in 12 isolated, blood-perfused rabbit hearts with isotope dilution studies at constant coronary perfusion. After a control injection of tracers, NFI was induced for 30-60 minutes. After coronary reflow, repeat tracer injections were given at early RPF (5-15 minutes of RPF) and late RPF (40-60 minutes of RPF).

Comparative myocardial extraction of two technetium-labeled BATO derivatives (SQ30217, SQ32014) and thallium.

The transcapillary exchange of a new class of 99mTc-labeled compounds (BATO) were compared to 201Tl in isolated, blood perfused rabbit hearts. During variable blood flow (0.15-2.

Comparison of hypoxia and ouabain effects on the myocardial uptake kinetics of technetium-99m hexakis 2-methoxyisobutyl isonitrile and thallium-201.

Effects of hypoxia and ouabain on transcapillary exchange of [99mTc]hexakis (2-methoxyisobutylisonitrile) [SESTAMIBI, also known as MIBI or HEXAMIBI] and 201TI were investigated with indicator-dilution studies using isolated rabbit hearts. Peak myocardial extraction (Emax), permeability-surface area products (PScap), and net myocardial extraction (Enet) were compared among serial injections during constant coronary flows. Overall, measures of transcapillary transport (Emax and PScap) for SESTAMIBI were significantly lower (p less than 0.

Comparison of the myocardial uptake of a technetium-labeled isonitrile analogue and thallium.

The myocardial transmicrovascular transport of thallium-201 (201Tl) and technetium-99m hexakis(2-methoxyisobutylisonitrile) (MIBI) were compared during variable blood flow levels in nine blood-perfused, isolated rabbit hearts. Seventeen injections of radiolabeled albumin and EDTA as well as 201Tl and MIBI were performed by indicator-dilution techniques. When coronary flow was varied from 0.

The effect of dipyridamole on transmural blood flow gradients.

The effect of dipyridamole (DP) on subendocardial (ENDO) and subepicardial (EPI) blood flow in stenosed and normal regions was determined with radioactive microspheres before and after intravenous infusion of 0.08 mg/kg.min-1 of DP in two groups of dog hearts in situ.