[Radionuclide pulmonary perfusion imaging in evaluating pulmonary hypertension in patients with congenital heart disease]

OBJECTIVE

To evaluate the degree of pulmonary hypertension in patients with congenital heart disease (CHD) by using radionuclide pulmonary perfusion imaging.

METHOD

The pulmonary perfusion in 81 patients with left to right cardiac shunts was examined by scintigram with macroaggregates of (99m)Tc-labeled human serum albumin (PPS). PPS was analyzed for (1) lung regional radionuclide count (LRC), (2) right upper and lower lung count ratio (RULR), (3) kidney count ratio (KCR). The results were compared with those of cardiac catheterization exam.

RESULT

There were correlation between mean pulmonary arterial pressure (mPAP), total pulmonary resistance (TPR), and PPS (KCR, RULR with mPAP gamma = 0.25, 0.35; LRC, KCR with TPR gamma = -0.34, 0.29). Five patients repeated PPS test after early operation. There were no changes in PPS.

CONCLUSION

The degree of reversibility of pulmonary hypertension in patients with CHD could be quantitatively analysed by PPS.

Phonological and acoustic bases for earliest grammatical category assignment: a cross-linguistic perspective

Maternal infant-directed speech in Mandarin Chinese and Turkish (two mother-child dyads each; ages of children between 0;11 and 1;8) was examined to see if cues exist in input that might assist infants' assignment of words to lexical and functional item categories. Distributional, phonological, and acoustic measures were analysed. In each language, lexical and functional items (i.e. syllabic morphemes) differed significantly on numerous measures. Despite differences in mean values between categories, distributions of values typically displayed substantial overlap. However, simulations with self-organizing neural networks supported the conclusion that although individual dimensions had low cue validity, in each language multidimensional constellations of presyntactic cues are sufficient to guide assignment of words to rudimentary grammatical categories.

[Effects of electrical acupuncture on the cerebral blood flow and the pial microcirculatory blood flow in dogs]

Using electromagnetic flowmeter and Laser Coppler Microcirculatory flowmeter, we studied the effect of electrical acupuncture at Zusanli (ST 36) and Quchi (LI 11) on cerebral blood flow and pial microcirculatory blood flow in dogs. The results showed that the cerebral blood flow increased remarkably, while the cerebral vascular resistance (CUR) decreased 1 min. after the acupuncture start and 20, 30, 60, 90 min. after stopping of the stimulation, and the blood flow of the pial microvessels increased 1, 5, 10 min. after starting of acupuncture and 30 min. after stopping of the stimulation. It indicates that one of the mechanisms of treatment of cerebral vascular diseases with acupuncture is that acupuncture increases the cerebral blood flow and improve the pial microcirculation.

Conduction block in acute and chronic spinal cord injury: different dose-response characteristics for reversal by 4-aminopyridine

The effect of the potassium channel blocker, 4-aminopyridine (4-AP), on conduction of action potentials in injured guinea pig spinal cord axons was measured using isolated tracts in oxygenated Krebs' solution at 37 degrees C. The dose-response characteristics of acutely and chronically injured axons were compared. The maximal improvement of conduction occurred in acutely injured axons at a concentration of 100 microM 4-AP, but in chronically injured spinal cord at 10 microM. The threshold for significant response to 4-AP was between 0.5 and 1 microM in chronically injured cords, and between 1 and 10 microM following acute compression injury. The difference in susceptibility to potassium channel blockade may be related to underlying differences in the mechanism of conduction block at the two stages of injury. Initially, junctions between axons and myelin are acutely disrupted, altering primarily the leakage resistance of the myelin sheath and periaxonal space. In chronically injured cords, there is widespread but incomplete process of repair in the lesion site, which leaves many axons partially myelinated. The difference in sensitivity to 4-AP suggests there is also some modification of the accessibility of axonal potassium channel or a change in their affinity for the drug.

Acute and Delayed Toxicity Studies on the Antiherpesvirus Agents 5-Methoxymethyl-2′-Deoxycytidine and 5-Methoxymethyl-2′-Deoxyuridine

5-Methoxymethyl-2′-deoxycytidine (MMdCyd) and the corresponding deoxyuridine analogue, 5-methoxymethyl-2′-deoxyuridine (MMdUrd) are selective antiherpesvirus agents. MMdCyd (ED501.5 μM) is a more potent inhibitor of herpes simplex virus replication than MMdUrd (ED5030 μM) when maintained in the deoxycytidine form (deamination prevented). The 5′-triphos-phates, MMdCTP and MMdUTP, were synthesized, and incorporation into DNA by mitochondrial DNA polymerase γ was investigated. MMdCTP and MMdUTP were incorporated into DNA in place of dCTP and dTTP, respectively. The effect of MMdCyd and MMdUrd on cell growth (acute toxicity) and prolonged exposure (delayed cytotoxicity) in CEM cells was investigated. The two analogues did not exhibit acute or delayed toxicity (2 weeks exposure) up to 1000 μM. In contrast, at a concentration as low as 0.125 μM of 2′,3′-dideoxycytidine (ddC; control drug), the doubling time of the cells increased after 10 days. At higher concentrations, a very marked increase in doubling time was observed from 6 days onward with ddC treatment. The data suggest that in uninfected cells neither MMdUrd nor MMdCyd are anabolized to the triphosphate form in significant amounts. As a result, little or no MMdCTP or MMdUTP builds up in the mitochondria and thus delayed toxicity is not observed.

A comparison of 99mTc-MIBI myocardial SPET with electron beam computed tomography in the assessment of coronary artery disease

We compared technetium-99m methoxyisobutylisonitrile (MIBI) myocardial perfusion single-photon emission tomography (SPET) (MPS) and electron beam computed tomography (EBCT) in order to assess their respective value in the detection of coronary artery disease (CAD). 99mTc-MIBI SPET (stress-resting) and EBCT studies were performed in 51 patients with suspected CAD who underwent coronary angiography (CAG). CAG showed that of the 51 patients, 36 had coronary stenosis >/=50% while 15 had normal results. A moderate positive rank correlation was found between coronary calcification detected by EBCT and MPS score (rs=0.5283, P<0.01). The concordance between EBCT and MPS for the evaluation of CAD was 72.5% (37/51). The sensitivity of EBCT in detecting CAD in 51 patients was comparable to that of MPS (81% vs 94%, NS). However, the accuracy of EBCT was lower than that of MPS (78% vs 94%, P<0.025). As regards the detection of individual coronary artery disease, there was no significant difference in sensitivity between EBCT and MPS (65% vs 75%, NS); however, the specificity and accuracy of EBCT were lower than those of MPS (specificity: 77% vs 95%, P<0.005; accuracy 71% vs 85%, P<0.005). The sensitivity, specificity and accuracy of MPS in detecting single-vessel disease were higher than those of EBCT (sensitivity: 86% vs 42%, P<0.025; specificity: 96% vs 70%, P<0.025; accuracy: 93% vs 61%, P<0.005). However, no significant differences in the sensitivity, specificity and accuracy of MPS and EBCT were found in respect of multivessel disease.

IN CONCLUSION

99mTc-MIBI myocardial perfusion SPET and EBCT provide different information in the assessment of CAD. The sensitivity of EBCT for the detection of CAD is comparable with that of MPS; however, the specificity and accuracy of EBCT are lower than those of MPS. More reliable results will be obtained if both myocardial perfusion SPET and EBCT are performed.

Development of a school-based nutrition intervention for high school students: Gimme 5

PURPOSE

To describe a 4-year intervention targeting fruit/vegetable consumption by high school students.

DESIGN

This is a cohort study involving six pairs of schools (n = 12) matched on gender, race, enrollment, and location with schools randomly assigned within pairs to intervention or control conditions.

SETTING

Twelve Archdiocese of New Orleans high schools.

SUBJECTS

Cohort was defined as students (n = 2339) who were ninth-graders in the 1993-94 school year who provided baseline data.

INTERVENTION

Four components of the intervention are: (1) school-wide media-marketing campaign, (2) school-wide meal and snack modification, (3) classroom workshops and supplementary subject matter activities, and (4) parental involvement.

MEASURES

Focus groups were conducted for target population input and program development. Process evaluation included student feedback on media-marketing intervention materials and activities reported here. Process measures also included school meal participation, student characteristics, and verification of intervention activities.

RESULTS

Focus groups identified barriers to increased consumption of fruit and vegetables as lack of availability, variety, and inconsistency in taste. Student attitudes were favorable regarding a school program to improve diet and parental involvement. Low consumption of fruits/vegetables was reported. After a 2-month school-wide program introduction utilizing various media-marketing materials and activities, 93% of students were aware of the program and 96% could identify the healthy eating message.

CONCLUSIONS

Program development can be guided and enriched by student input via focus groups. Media-marketing activities effectively delivered health messages and attracted students' attention. Materials and activities used were acceptable channels for increasing awareness, positive attitudes, and knowledge about fruits/vegetables.

Differential effects of low and high concentrations of 4-aminopyridine on axonal conduction in normal and injured spinal cord

Blockade of potassium channels with the drug 4-aminopyridine has been shown to effect recovery of action potential conduction in myelinated axons under a variety of pathological conditions, but the mechanism and significance of this phenomenon are not completely understood. This study examined the effects of a range of 4-aminopyridine concentrations on conduction in an experimental model of chronic spinal cord injury in guinea-pigs, using sucrose-gap recording from isolated spinal cord strips. The amplitude of the compound action potential increased in response to bath application of 4-aminopyridine, with a threshold between 0.5 and 1 microM and the peak response between 10 and 100 microns. Conduction was suppressed at concentrations of 1 and 10 mM. Uninjured white matter showed no effect on the compound potential of 4-aminopyridine below 1 mM, but there was a similar suppression at concentrations above 1 mM, accompanied by marked membrane depolarization. Peripheral nerve showed only slight action potential suppression and depolarization in the presence of 10 mM 4-aminopyridine. The sensitivity of injured axons to 1 microM 4-aminopyridine is consistent with the hypothesis that some beneficial effects of the drug seen in patients with spinal cord injury are related to improved conduction in myelinated axons, since cerebrospinal fluid levels of 4-aminopyridine should approach this concentration following clinical systemic doses, although it remains likely that synaptic effects also play a role. The blockade of action potential conduction produced by much higher levels of 4-aminopyridine in vitro is possibly a consequence of interference with the resting potential mechanism of the axon membrane, which appears to differ between central and peripheral nerve fibers.

Compression injury of mammalian spinal cord in vitro and the dynamics of action potential conduction failure

1. White matter strips from the ventral spinal cord of adult guinea pigs were isolated in vitro, and their electrophysiological characteristics and response to controlled focal compression injury were examined. A double sucrose gap technique was used for stimulation and recording at opposite ends of a 12.5 mm-diam central well superfused with oxygenated Krebs solution. 2. The compound action potential recorded with the sucrose gap was similar in form to single fiber potentials recorded with intra-axonal electrodes, including the presence of a prolonged depolarizing afterpotential. 3. Three types of conduction block resulting from compression were identified: an immediate, spontaneously reversible component, which may result from a transient increase in membrane permeability and consequent disturbance of ionic distribution; a second component that was irreversible within 1-2 h of recording, perhaps resulting from complete axolemmal disruption; and a third component, which may have been due to disruption of the myelin sheath, that appeared to be reversible with application of 10-100 microM of the potassium channel blocker 4-aminopyridine. 4. Conduction deficits--decreased amplitude and increased latency of the compound potential--were stable between 5 and 60 min postinjury, and their intensity corellated with the extent of initial compression over a full range of severity. 5. Stimulus-response data indicate that mechanical damage to axons in compression was evenly distributed across the caliber spectrum, suggesting that the susceptibility of large caliber axons seen histopathologically after injury in vivo may be based on delayed, secondary processes. 6. The model provides the ability to monitor changes in the properties of central myelinated axons after compression injury in the absence of pathological variables related to vascular damage. This initial investigation found no evidence of secondary deterioration of axons in the 1st h after injury, although there was evidence of both transient and lasting mechanical damage to axons and their myelin sheaths.

Myelination in the absence of galactocerebroside and sulfatide: normal structure with abnormal function and regional instability

The vertebrate nervous system is characterized by ensheathment of axons with myelin, a multilamellar membrane greatly enriched in the galactolipid galactocerebroside (GalC) and its sulfated derivative sulfatide. We have generated mice lacking the enzyme UDP-galactose:ceramide galactosyltransferase (CGT), which is required for GalC synthesis. CGT-deficient mice do not synthesize GalC or sulfatide but surprisingly form myelin containing glucocerebroside, a lipid not previously identified in myelin. Microscopic and morphometric analyses revealed myelin of normal ultrastructural appearance, except for slightly thinner sheaths in the ventral region of the spinal cord. Nevertheless, these mice exhibit severe generalized tremoring and mild ataxia, and electrophysiological analysis showed conduction deficits consistent with reduced insulative capacity of the myelin sheath. Moreover, with age, CGT-deficient mice develop progressive hindlimb paralysis and extensive vacuolation of the ventral region of the spinal cord. These results indicate that GalC and sulfatide play important roles in myelin function and stability.

Uncoupling histogenesis from morphogenesis in the vertebrate embryo by collapse of the transneural tube potential

We have shown that unidirectional pumping of Na+ out of the neural tube's luminal fluids in amphibian embryos produces a large potential difference (40-90 mV, lumen negative to the abluminal surface). This transneural tube potential (TNTP) is analogous to the Na+ dependent transepithelial potential (TEP) that exists across surface ectoderm. This TEP is retained in ectoderm after it is internalized when the neural folds fuse to form the neural tube. The TNTP can be markedly reduced for several hours by injection of the Na+ channel blockers amiloride or benzamil into the lumen by iontophoresis through microelectrodes. Here we describe the effect of TNTP modification on developmental anatomy. Axolotl embryos possessing a fused and closed neural tube (stage 21-23) were injected with either amiloride or benzamil and allowed to continue development for 36-52 hr. These were compared to control embryos injected with vehicle alone, or to embryos in which amiloride or benzamil was iontophoresed just beneath surface ectoderm. All embryos in which the TNTP was reduced were grossly defective. These were characterized by a disaggregation of the cells comprising the structures that had already begun to form (otic primordia, brain, spinal cord, notochord) as well as a failure in the development of new structures. Remarkably, some of these embryos displayed continuing development of external form in the complete absence of concomitant internal histogenesis. We discuss the ways in which a large endogenous voltage gradient associated with an epithelial potential difference (the TNTP) may be required both for the structural integrity of the early neuroepithelium, and a prerequisite for normal morphogenesis.

Three-dimensional gradients of voltage during development of the nervous system as invisible coordinates for the establishment of embryonic pattern

We are interested in the generation of endogenous electric fields associated with ionic currents driven through the vertebrate embryo by the transepithelial potential of its surface ectoderm. Using a non-invasive vibrating electrode for the measurement of ionic current, we have provided measurements of currents traversing amphibian embryos, and a preliminary report of the internal, extracellular voltage gradient under the neural plate which polarizes the embryo in the rostral/caudal axis (Metcalf et al. [1994] J. Exp. Zool. 268:307-322). Here we complete a description of this gradient in electrical potential (ca. 10 mV/mm, caudally negative), describe a simultaneous gradient organized in the medial/lateral axis (ca. 5-18 mV/mm, negative at the margins of the neural folds), and describe their appearance and disappearance during ontogeny of the axolotl embryo. Both voltage gradients are not expressed until neurulation, and disappear at its climax. This appearance and disappearance correlates with the shunting of current out of the lateral margins of the neural folds in rostral regions of the embryo beginning at stage 15, and is not associated with a more substantial current leak from the blastopore which appears at gastrulation. A steady blastopore current is still present after neural tube formation when intra-embryonic electric fields have been extinguished. We discuss the direct experimental tests supporting the hypothesis that these extracellular electric fields both polarize the early vertebrate embryo and serve as cues for morphogenesis and pattern.

Comparison of tomographic and planar radionuclide ventriculography in the assessment of regional left ventricular function in patients with left ventricular aneurysm before and after surgery

METHODS AND RESULTS

To compare tomographic and planar radionuclide ventriculography (RNVG) in assessing regional left ventricular (LV) function and predicting improvement in LV ejection fraction (LVEF) after operation in patients with LV aneurysm, 18 patients with aneurysm underwent both tomography and planar RNVG 1 month before and 3 weeks to 6 months after aneurysmectomy and coronary artery bypass grafting. All patients also underwent preoperative contrast angiography at catheterization. The percent shortening of the apical, anterior, lateral, inferior, and basal segments was calculated from tomographic long-axis and short-axis slices and corresponding planar images (anterior and 30- and 70-degree left anterior oblique views). No significant differences in anterior, apical, and lateral percent shortening were apparent before aneurysmectomy between tomographic and planar studies. However, preoperative basal percent shortening was 47% +/- 13% from tomographic and 28% +/- 14% from planar images (p < 0.001). Preoperative tomography generally agreed better with contrast angiographic results than did planar imaging. After aneurysmectomy, basal function improved to 57% +/- 12% (p < 0.01) by tomography. For all patients, LVEF increased from 29% +/- 8% before to 38% +/- 9% (p < 0.01) after aneurysmectomy. However, the greatest improvement (31% +/- 11% to 41% +/- 9%; p < 0.01) was in the 15 patients with greater than 30% basal shortening by tomography before aneurysmectomy; in contrast, no change of LVEF occurred in the three patients with lesser preoperative basal percent shortening. Moreover, greater than 30% basal percent shortening by tomography before aneurysmectomy identified the group most likely to have an increase in LVEF of 5% or more from before to after aneurysmectomy. Prediction of postoperative results was not possible from preoperative planar data. Thus in patients with LV aneurysm, tomographic RNVG appears to provide information that is different and more accurately predictive of results after aneurysmectomy than that available from planar imaging.

Embryonic neuroepithelial sodium transport, the resulting physiological potential, and cranial development

We have shown that the amiloride/novobiocin-sensitive sodium transport system of adult animal integuments is first observed in embryonic surface ectoderm and show here that this physiology is retained in this ectoderm following the closure of the neural folds. Unidirectional transport of Na+ out of the neural tube lumen results in a potential difference on the order of 40-90 mV, negative with respect to the abluminal surface. This transneural tube potential can be collapsed by iontophoresis of Na+ channel blockers amiloride or benzamil into the lumen, leading to severe cranial defects and incomplete morphogenesis. Modestly increasing the transneural tube potential with injection of novobiocin into the lumen also produces a lesser degree of developmental abnormality. We discuss the ways in which this physiology may help control the organization of the early nervous system.

Mammalian cortical astrocytes align themselves in a physiological voltage gradient

Astrocytes obtained from primary cultures of newborn rat cerebral cortex show a marked structural rearrangement to weak (50-500 mV/mm) applied voltage gradients. Astrocytes reorient their processes so that the cells are aligned perpendicular to the voltage gradient. At field strengths of 100 mV/mm or greater, this realignment occurs in over 90% of the cell population. Furthermore, these magnitudes of electric fields completely eliminate any parallel alignments originally observed prior to application of the voltage. Realignment usually occurs by a withdrawal, followed by an extension, of cell processes. These responses occur at voltage gradients within the physiological range that naturally exist across the neural tube during early development. We suggest the possibility that architectural arrangements of developing glia and, subsequently, neurons may be regulated by endogenous transepithelial potentials that exist across embryonic neuroepithelium.

[Analysis of NK cell activity in patient with pulmonary tuberculosis]

Activity of NK cell of 30 cases pulmonary TB and 30 normal adult were determined. The result is that activity of NK cell is markedly reduced in the pulmonary TB than that of controls (P less than 0.001). And it is not related to course, or lesions, or sputum smears or cultures or cavities (P greater than 0.05).