Anoxia/reoxygenation-induced tolerance with respect to polymorphonuclear leukocyte adhesion to cultured endothelial cells. A nuclear factor-kappaB-mediated phenomenon

The best available evidence of inhibitory conditioning in vertebrates comes from experiments in which variants of A+/AB- and A+/B- training were compared in terms of response to B in summation and retardation tests, the results suggesting that inhibition is generated by nonreinforcement as an increasing function of the excitatory value of the setting. We report here 7 experiments with foraging honeybees (Apis mellifera) that failed to show a difference in the effects of the 2 treatments. On the basis of previous experiments as well as supplementary experiments whose results give no reason to doubt the sensitivity of the training techniques and measures used, our consistently negative results may mean either that inhibition in honeybees is generated by nonreinforcement independently of the setting or that there is no inhibitory conditioning at all in honeybees--that the only associative function of nonreinforcement is to reduce excitatory strength.     

Acyclophostin: a ribose-modified analog of adenophostin A with high affinity for inositol 1,4,5-trisphosphate receptors and pH-dependent efficacy

The developing legs of Drosophila are subdivided into proximal and distal domains by the activity of the homeodomain proteins Homothorax (Hth) and Distal-less (Dll). The expression domains of Dll and Hth are initially reciprocal. Wingless and Dpp define both domains by activating Dll and by repressing Hth in the distal region of the disc. Wg and Dpp do not act through Dll to repress Hth. Hth functions to reduce the sensitivity of proximal cells to Wg and Dpp. This serves to limit the effective range of these signals in regulating later-acting genes such as Dac. We present evidence that proximal and distal cells tend to sort-out from one another. Cells forced to express Hth are unable to mix with distal cells. Likewise, cells forced to express Dll are unable to mix with proximal cells. Clones of cells unable to express Dll in the distal region sort-out from the disc. Clones of cells unable to express Hth lose the specialized population of cells at the interface between proximal and distal territories and cause fusion between body wall and leg segments. These observations suggest that sorting-out behavior of Hth- and Dll-expressing cells contributes to subdivision of the leg into proximal and distal domains.     

Impact of sonography on the diagnosis and treatment of acute lower abdominal pain in children and young adults

OBJECTIVE: Our purpose was to evaluate the impact of sonographic data on clinical physicians' diagnostic confidence and their treatment of children and young adults with acute lower abdominal pain. SUBJECTS AND METHODS: Senior surgical and emergency department staff completed questionnaires before and after abdominal sonography was performed on 94 of 101 consecutive children and young adults with acute lower abdominal pain, pelvic pain, or both. Physicians who were unaware of sonographic data stated the most likely diagnosis and their level of confidence in their diagnosis and then formulated clinical plans. After they were given sonographic data, physicians again stated the most likely diagnosis, estimated their level of confidence, and formulated revised treatment plans. RESULTS: Sonographic data resulted in revised clinical diagnoses in 52% of the patients. Overall, the gain in diagnostic confidence for the entire study population was 33% (95% confidence interval [CI], 27-38%; p < .0001). The impact on the physicians' confidence was greater in those children and young adults whose diagnoses changed after sonography (mean increase in physicians' confidence, 48.3%; 95% CI, 47-75%). In patients whose diagnoses were not changed after sonography, the mean increase in physicians' confidence was 17.6% (95% CI, 11-24%; p < .0001 [analysis of variance]). Physicians used sonographic data to change initial treatment plans in 43 patients (46%). Of these 43 patients, a lower intensity of care was given to 30 patients (70%) and a higher intensity to 13 patients (30%). CONCLUSION: Sonographic data frequently changed initial clinical diagnoses, thus increasing diagnostic confidence and changing clinical treatment decisions in the setting of acute lower abdominal pain in children and young adults.     

Poly-3-hydroxybutyrate in Legionella pneumophila, an energy source for survival in low-nutrient environments

Chloroform-soluble material was extracted from two strains of L. pneumophila serogroup 1 following growth in continuous culture. The purified material was identified as poly-3-hydroxybutyrate (PHB) by nuclear magnetic resonance spectroscopy and by gas chromatography-mass spectrometry. PHB yields of up to 16% of cell dry weight were extracted from culture samples. The PHB was located in electron-dense intracellular inclusions, which fluoresced bright yellow when stained with the lipophilic dye Nile red. A Nile red spectrofluorometric assay provided a more accurate and reliable determination of the PHB content. PHB accumulation increased threefold during iron-limited culture and was inversely related to the concentration of iron metabolized. Chemostat-grown cells survived in a culturable state for at least 600 days when incubated at 24 degreesC in a low-nutrient tap water environment. Nile red spectrofluorometry and flow cytometry demonstrated that PHB reserves were utilized during starvation. PHB utilization, as revealed by the decline in mean cellular fluorescence and cell complexity, correlated with loss of culturability. Fluorescence microscopy provided visual evidence of PHB utilization, with a marked reduction in the number of Nile red-stained granules during starvation. Heat shock treatment failed to resuscitate nonculturable cells. This study demonstrates that L. pneumophila accumulates significant intracellular reserves of PHB, which promote its long-term survival under conditions of starvation.     

Proton and neutron excitations in superdeformed 150Tb

To determine which of two treatments for reducing ischemic injury after temporal focal ischemia is more effective, the effects of mild (33 degrees C) intraischemic hypothermia were compared with those of mannitol, the most commonly used neuroprotective agent. Four groups of Sprague-Dawley rats underwent 1 hour of endovascular middle cerebral artery occlusion followed by 23 hours of normothermic reperfusion. The four experimental groups were as follows: Group A, saline control; Group B, mannitol (25%, 1 g/kg); Group C, hypothermia; and Group D, hypothermia plus man-nitol. Laser-Doppler estimates of cortical blood flow showed that hypothermia did not affect blood flow during ischemia or reperfusion. Mannitol increased cortical blood flow during ischemia and reperfusion under both normothermic and hypothermic conditions (p < 0.05). Neurological deficit was significantly less severe in treated rats (Group B, p < 0.05; Group C or D, p < 0.01) than in controls (Group A). Infarct volume, measured on semiserial Nissl-stained sections, was significantly smaller in treated rats (p < 0.01) than in controls. Infarct volume was also significantly smaller in rats treated with hypothermia than in those treated with mannitol (Group C vs. Group B, p < 0.05); there was no difference between rats treated with mannitol and those treated with mannitol and hypothermia. All three treatments reduced infarct area in the ischemic penumbra; hypothermia with or without mannitol also reduced infarct area in the ischemic core. These results demonstrate that both mild intraischemic hypothermia and mannitol reduce infarct size and neurological deficit: hypothermia reduces infarct size more effectively than mannitol, and mannitol adds no significant protection to hypothermia, whereas hypothermia adds significant protection beyond that afforded by mannitol after brief focal ischemia followed by reperfusion in rats. The results suggest that mild intraischemic hypothermia alone, or in combination with mannitol, may be useful in avoiding ischemic injury from temporary vessel occlusion during cerebrovascular surgery.     

Smooth muscle alternative splicing induced in fibroblasts by heterologous expression of a regulatory gene

Alternative splicing is a common mechanism for regulating gene expression in different cell types. In order to understand this important process, the trans-acting factors that enforce the choice of particular splicing pathways in different environments must be identified. We have used the rat alpha-tropomyosin gene as a model system of tissue-specific alternative splicing. Exon 3 of alpha-tropomyosin is specifically inhibited in smooth muscle cells allowing the alternative inclusion of exon 2. We have used a novel gene transfer and selection strategy to detect a gene whose expression in fibroblasts is sufficient to switch them to smooth muscle-specific splicing of alpha-tropomyosin and also alpha-actinin. Extracts from the regulating fibroblasts contain an apparently novel 55 kDa protein which binds to RNA elements required for regulation of tropomyosin splicing. This protein is not detected in extracts of non-regulating cells and is therefore a strong candidate cell-specific splicing regulator. These experiments advance our understanding of smooth muscle splicing regulation as well as establishing a means for direct cloning of tissue-specific splicing regulators which have so far been refractory to biochemical analysis.     

Management of thoracolaryngopelvic dysplasia

We report a family in which three members have thoracolaryngopelvic dysplasia (Barnes' syndrome). This family illustrates the phenotypic variability seen in this rare clinical entity and highlights the medical and surgical management necessary in such cases.     

Quantitation of 5-fluorouracil catabolism in human liver in vivo by three-dimensional localized 19F magnetic resonance spectroscopy

The development of clinical applications of 19F magnetic resonance (MR) spectroscopy of 5-fluorouracil (5-FU) has been limited by the inability to localize 19F spectra to specific regions of interest, making it difficult to quantitate drug and metabolite concentrations accurately. To develop methodology for quantitation, we studied the liver of patients receiving rapid bolus i.v. injections of 5-FU. In serial studies, 5-FU disappeared from the liver within 17-26 min, and its catabolite, alpha-fluoro-beta-alanine (FBAL), rose to reach a plateau after 40 min. A high peak level of fluoro-ureido-propionic acid preceded that of FBAL in only one patient, and dihydrofluorouracil was never observed. During the plateau, we obtained MR imaging-directed 19F MR spectra localized using three-dimensional chemical shift imaging. The spin-lattice relaxation time of FBAL in liver, measured using a variable nutation angle method, was 1.6 +/- 0.2 s (mean +/- SD; n = 5). The concentration of FBAL at 60 +/- 10 min after injection was 1.0 +/- 0.2 mm in liver (mean +/- SD; n = 7). This amount represents approximately 20% of the injected dose and 1.4 times the initial hepatic 5-FU concentration. Our approach may permit one to obtain molar concentrations of fluoropyrimidine metabolites simultaneously in hepatic cancers and surrounding liver, and it helps expand pharmacokinetic modeling of fluoropyrimidine catabolism.