Navigator gated high temporal resolution tissue phase mapping of myocardial motion.

Data acquisition for phase contrast velocity mapping of myocardial motion is typically based on multiple breath-held 2D measurements with limited acquisition duration and consequently relatively poor temporal resolution. In order to overcome the limitations of breath-hold acquisitions, an improved navigator-guided technique was implemented based on 2 navigator signals within each cardiac cycle in combination with paired acceptance and rejection criteria of successive navigator signals. Respiratory gated phase contrast measurements with 3-directional velocity encoding were performed in 12 healthy volunteers in basal, midventricular, and apical locations of the left ventricle during free breathing with a temporal resolution of 13.8 ms. Results were compared to standard breath-hold measurements with a temporal resolution of 69 ms. Data from the high temporal resolution study revealed details in left ventricular motion patterns that were previously not seen in phase contrast measurements and are only known from echocardiography. The proposed navigator gated technique for high temporal resolution velocity mapping is, therefore, highly promising for the detection of local and global motion abnormalities in patients with disturbed left ventricular performance, such as diastolic dysfunction.     

A new gene deletion in the alpha-like globin gene cluster as the molecular basis for the rare alpha-thalassemia-1(--/alpha alpha) in blacks: HbH disease in sickle cell trait

A novel deletion of at least 26 kilobase of DNA, including both alpha- globin genes, the psi alpha- and psi zeta-globin genes, but sparing the functional zeta-gene was found in a 10-year-old black boy with HbH disease and sickle cell trait. This particular deletion has not previously been described in blacks. Its existence makes it likely that the absence of Hb Barts hydrops fetalis in blacks is due to the rarity of the chromosome lacking two alpha-globin genes rather than a result of early embryonic death due to the failure to synthesize embryonic hemoglobins because of deletion of functional zeta-globin genes.     

The regulatory role of interleukin 2-responsive T lymphocytes on early and mature erythroid progenitor proliferation

To analyze the role of T lymphocytes in human erythropoiesis, we evaluated the effect of recombinant interleukin 2 (IL 2) on marrow CFU- E and BFU-E colony formation in vitro. IL 2 resulted in an increase in CFU-E and BFU-E colony numbers in a dose-dependent manner. This increase could be prevented by anti-Tac, a monoclonal antibody to the IL 2 receptor. Moreover, anti-Tac on its own resulted in an overall decrease in colony numbers. Depletion of marrow adherent cells did not alter the effect of either IL 2 or anti-Tac on colony growth. Following the removal of marrow T lymphocytes, CFU-E and BFU-E colony formation proceeded normally; however, the effects of IL 2 and anti-Tac were markedly diminished. Readdition of T lymphocytes to the cultures restored the IL 2 effect. Although T lymphocytes were not themselves essential for in vitro erythropoiesis, our studies suggest that IL 2 and IL 2-responsive T cells can regulate both early and mature stages of erythroid differentiation.     

Oxidized lipid-mediated alterations in proteoglycan metabolism in cultured pulmonary endothelial cells

Compared to cholesterol or linoleic acid (18:2), oxidized lipids such as cholestan-3β,5,6β-triol (triol) and hydroperoxy linoleic acid (HPODE) markedly impair endothelial barrier function in culture [Hennig and Boissonneault, 1987; Hennig et al. 1986]. Because proteoglycans contribute to vascular permeability properties, the effects of cholesterol and 18:2 and their oxidation products, triol and HPODE, on endothelial proteoglycan metabolism were determined. While cholesterol was without effect, a concentration-dependent decrease in cellular proteoglycans (measured by ³⁵S incorporation) was observed after exposure to triol. Compared to control cultures, cholesterol reduced mRNA levels for the proteoglycans, perlecan and biglycan. Triol had a similar effect on biglycan but not on perlecan mRNA levels. Compared to 18:2, 1, 3 and 5 μM HPODE depressed cellular proteoglycans. Perlecan mRNA levels were reduced more by HPODE when compared to 18:2. Biglycan mRNA levels were reduced by 3 μM, but not by 5 μM HPODE. These data demonstrate that oxidized lipids such as triol and HPODE can decrease cellular proteoglycan metabolism in endothelial monolayers and alter mRNA levels of major specific proteoglycans in a concentration-dependent manner. This may have implications in lipid-mediated disruption of endothelial barrier function and atherosclerosis.     

O等位基因引起ABO基因型与表现型定型差异

保证输血时血清学方面的安全,首要的是对受血者与献血者ABO血型定型,血清学检查通常分两个步骤.正定型通常使用鼠源单克隆抗体检测红细胞表面是否存在A或B抗原.互补的实验即反定型,利用当红细胞上缺乏A或B抗原时,人群可天然产生相对应的抗体的原理,检测血清中是否存在抗-A或者抗-B抗体.确定了受血者红细胞表面的ABO抗原以及血浆中的抗体,便能确定血型,为其提供相合的血液.     

Supraventricular arrhythmias in experimental myocardial infarction

Summary The electrophysiological mechanisms underlying supraventricular dysrhythmias that accompany acute myocardial infarction were studied in rabbits subjected to ligation of right coronary artery. In vivo, sinus bradycardia, atrioventricular block and rapid atrial arrhythmias were observed 2 to 5 hours after coronary occlusion; evidence of ventricular arrhythmias was absent. The bradyarrhythmias were markedly improved after iv administration of atropine. The infarcted hearts were then removed and the isolated sinoatrial (SA) node, right atrium and atrioventricular (AV) node were studied with intracellular microelectrodes in vitro. Rapid, repetitive atrial depolarizations occurring spontaneously or initiated by premature atrial stimulation were observed only in preparations obtained from infarcted hearts. In disseminated areas localized within the SA node and the atrium, the subendocardial fibers had a reduced action potential amplitude but showed also normal potentials in other regions as compared with noninfarcted preparations. Sinus rate, poststimulatory sinus-node recovery time, intraatrial conduction and the parameters of AV nodal function including action potential amplitude and conduction were not significantly different in preparations isolated from infarcted and noninfarcted hearts. The results suggest that the observed bradyarrhythmias accompanying acute myocardial infarction may be partly due to a vagomimetic reflex whereas the supraventricular tachycardias seem to result from direct cellular damage.

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Supraventrikuläre Arrhythmien bei experimentellem MyokardinfarktIn-vivo- und In-vitro-Befunde

Zusammenfassung Die elektrophysiologischen Mechanismen von supraventrikulären Arrhythmien bei akutem Myokardinfarkt wurden an Kaninchen untersucht, bei denen die rechte Koronararterie unterbunden wurde. In vivo wurden 2 bis 3 Stunden nach Koronarverschluß eine Sinusbradykardie, atrioventrikuläre Blockierungen und atriale Tachykardien beobachtet. Atropin (i.v.) führte zu einer signifikanten Rückbildung der Bradykardien. Anschließend wurden die infarzierten Herzen freipräpariert und der rechte Vorhof einschließlich sinuatrialem (SA) und atrioventrikulärem (AV) Knoten mit intrazellulären Mikroelektroden in vitro untersucht. Im Vergleich zu Kontrollpräparaten von nichtinfarzierten Herzen wurden bei Vorhöfen von infarzierten Herzen folgende Befunde beobachtet:1. Spontane atriale Tachykardien. 2. Abnahme der Amplitude des Aktionspotentials in disseminierten subendokardialen atrialen und SA nodalen Fasern, aber normale Aktionspotentiale bei der Mehrzahl der untersuchten Fasern. 3. Normale Sinusfrequenz, poststimulatorische Sinusknotenerholungszeit, intraatriale und AV nodale Leitungszeiten. Die Befunde deuten auf einen vagomimetischen Reflex als überwiegende Ursache der in vivo beobachteten Bradykardien hin, während die supraventrikulären Tachykardien möglicherweise durch eine direkte Schädigung der Zellmembran bedingt sind.

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With 8 figures and 2 tables

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The studies were supported by the German Research Foundation within the SFB 90 Cardiovaskuläres System. Dr.Mizutani is a Research Fellow of the Alexander von Humboldt Stiftung.     

Morphometry of the retrobulbar human optic nerve: comparison between conventional sonography and ultrafast magnetic resonance sequences

PURPOSE: To compare different methods for quantification of optic nerve and nerve sheath diameter. To apply a novel magnetic resonance protocol using half-Fourier acquired single-shot turbo spin-echo (HASTE) sequences to analyze optic nerve dimensions. METHODS: Measurements were taken in right eyes of 33 subjects whose median age was 25 years. A-scan ultrasonography was repeated three times in straight gaze. B-scan ultrasonography was repeated three times in straight gaze and abduction. HASTE sequences were applied in straight gaze, analyzed twice by two different radiologists, and completely repeated in a subset of 10 subjects; 95% confidence intervals and coefficients of variation were calculated. RESULTS: HASTE sequences yielded high contrast between cerebrospinal fluid and optic nerve parenchyma. Acquisition time for each sequence was 1.5 seconds per slice. Optic nerve diameters decreased from 3.23 mm at 5 mm to 2.67 mm at 15 mm behind the eye. Sheath diameters decreased from 5.72 mm to 3.98 mm. A- and B-scan ultrasonography yielded significantly smaller diameters. For HASTE sequences, the coefficients of variation ranged from 2% to 7% and were significantly smaller than those obtained with ultrasonographic measurements (9%-13%). CONCLUSIONS: The precision of magnetic resonance imaging exceeds that of ultrasonographic methods for determining optic nerve and nerve sheath diameters. HASTE sequences appear particularly appropriate for investigating the retrobulbar optic nerve complex and may be useful in future studies quantifying axonal loss within the optic nerve.     

Pontocerebellar atrophy is the hallmark neuroradiological finding in late-onset Tay-Sachs disease

Neurological Sciences - Late-onset Tay-Sachs disease (LOTS) is a form of GM2 gangliosidosis, an autosomal recessive neurodegenerative disorder characterized by slowly progressive cerebellar ataxia,...