Fission before K equilibration.
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Journal Article↗
Biomedical subjects
J Xu
Publications and source records attributed to J Xu.
Purinergic modulation of neural control of cardiac function.
1. The purine nucleotide adenosine 5'-triphosphate (ATP) and its related nucleoside, adenosine (Ado), exert pronounced electrophysiologic, inotropic, lusitropic and metabolic effects in the mammalian heart. 2. These effects are the result of direct actions of these compounds on cardiac myocytes and endothelial cells, mediated by cell surface receptors. 3. In addition, ATP and Ado can stimulate neural elements inside and outside the heart and thereby modulate neural control of cardiac function. These latter actions of ATP and Ado are briefly reviewed and their hypothetical physiological role is outlined.
Adenosine↗
Interferons block protein kinase C-dependent but not-independent activation of Raf-1 and mitogen-activated protein kinases and mitogenesis in NIH 3T3 cells.
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Retraction Notice↗
Induction of hepatoma cell apoptosis by c-myc requires zinc and occurs in the absence of DNA fragmentation.
Since c-myc expression is increased during apoptosis in toxin-induced liver injury in vivo, the role of c-myc in liver cell apoptosis was investigated. The human hepatoma cell line HuH-7, which constitutively expresses c-myc, was stably transfected with sense and antisense c-myc expression vectors under the control of the zinc-inducible metallothionein promoter. None of the three cell types (wild-type, sense c-myc, or antisense c-myc) underwent apoptosis when cultured in serum-free medium (SFM). With the addition of SFM plus 37.5 microM zinc, wild-type and sense c-myc-expressing cells underwent rapid cell death, whereas antisense c-myc-expressing cells exhibited increased survival. This cell death had the light, fluorescent, and electron microscopic appearance of apoptosis, but did not result in DNA fragmentation. This apoptosis could be terminated by the addition of medium containing 2% fetal calf serum or the overexpression of bcl-2 but not by supplementation with specific growth factors. Altering c-myc expression did not affect cellular metallothionein mRNA levels or the rate of cell death from copper or cadmium. The requirement for zinc and absence of DNA fragmentation in c-myc-induced hepatoma cell apoptosis under serum-free conditions provides further evidence of the complex regulation of apoptosis in different cell types.
1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
Electrophysiological-anatomic correlates of ATP-triggered vagal reflex in the dog. III. Role of cardiac afferents.
To test the hypothesis that the asymmetry in the afferent traffic of the intra-right atrium (RA) ATP-triggered vagal reflex is due to the stimulation by ATP of extrapulmonary (i.e., cardiac) vagal chemosensitive afferent terminals, ATP, adenosine, and capsaicin were given into the canine RA and the aortic root (AR; n = 12); ATP and adenosine were also administered into the left common carotid artery and the descending aorta (n = 6). The negative chronotropic action [i.e., suppression of sinus node (SN) automaticity] of the test compounds and time to peak effect (tp) were determined. Under baseline conditions, ATP given into the left common carotid artery had a relatively very small effect. ATP given into the descending aorta had no effect. In contrast, intra-RA and intra-AR ATP markedly suppressed SN automaticity, the former less than the latter; the opposite was true for capsaicin. Intra-RA adenosine was much less potent than intra-RA ATP. The tp of intra-RA ATP and intra-RA adenosine were larger than the tp of intra-AR ATP. Pulmonary denervation did not alter the effects of intra-RAATP, intra-ARATP, or intra-AR capsaicin but almost abolished the effect of intra-RA capsaicin. Subsequent bilateral, but not left, cervical vagotomy markedly reduce the effects of ATP and eliminated the difference between the effects of ATP and adenosine. In addition, tp of intra-RA ATP and intra-AR ATP increased substantially and were similar to tp of adenosine. It was concluded that 1) ATP can stimulate vagal afferent terminals not only in the lungs but also in the heart, 2) the latter constitutes the vagal component of the negative chronotropic action of intra-RA or intra-AR ATP on SN automatically, and 3) the asymmetry in the vagal afferent traffic elicited by ATP in the heart (i.e., right vagal dominance) supersedes the symmetrical vagal afferent traffic triggered by intrapulmonary ATP.
Adenosine↗
A novel guinea pig heart model for studying AV nodal conduction and triggered activity in vivo.
A novel model is described that enables for the first time the recording of the His bundle electrogram (HBE), monophasic action potential (MAP), and early (EAD) and delayed (DAD) afterdepolarizations in the guinea pig heart in vivo. In this model, custom-made catheter electrodes have been used; their detailed design, a recipe for their construction, and the modes of their operation are given in detail. In addition, examples of experimental data obtained using this model are given. These include values of atrial-to-His bundle and His bundle-to-ventricle intervals, as well as DADs associated with digoxin-induced ventricular arrhythmias. The present model is a small and relatively inexpensive model in which studies of atrioventricular nodal conduction, as well as afterdepolarizations/triggered activity, can be performed in vivo.
Action Potentials↗
Renal ischemic-reperfusion injury in L-selectin-deficient mice.
L-selectin on leukocyte surfaces mediates cell rolling on endothelium. L-selectin blockade with antibodies attenuated ischemic-reperfusion injury (IRI) in heart and skeletal muscle, but its role in renal IRI is unknown. We evaluated the role of L-selectin in renal IRI using L-selectin-deficient mice. Neutrophil migration to chemically inflamed peritoneum was reduced by 47% (P < 0.01) in L-selectin-deficient mice. Ischemia was induced by bilateral renal pedicle clamping for 30 min. Control and L-selectin groups had similar elevations of serum creatinine (1.8 +/- 0.3 vs. 1.7 +/- 0.2 mg/dl) and blood urea nitrogen (111 +/- 17 vs. 128 +/- 12 mg/dl) 24 h postischemia. Pathological assessment showed comparable degrees of tubular necrosis at 24 h. The postischemic increase in peritubular neutrophils per 10 high-power field was similar in control and L-selectin-deficient groups at 4 (28 +/- 10 vs. 22 +/- 5), 12 (245 +/- 80 vs. 236 +/- 78), and 24 h (130 +/- 12 vs. 156 +/- 18). These data argue against a significant role for L-selectin in renal IRI. Patho-physiological roles of L-selectin in vivo appear to be more complex than in vitro data would suggest.
Animals↗
Binaural inhibition is important in shaping the free-field frequency selectivity of single neurons in the inferior colliculus.
1. We have shown previously that under free-field stimulation in the frontal field, frequency selectivity of the majority of inferior colliculus (IC) neurons became sharper when the loudspeaker was shifted to ipsilateral azimuths. These results indicated that binaural inhibition may be responsible for the direction-dependent sharpening of frequency selectivity. To test the above hypothesis directly, we investigated the frequency selectivity of IC neurons under several conditions: monaural stimulation using a semiclosed acoustical stimulation system, binaural stimulation dichotically also using a semiclosed system, free-field stimulation from different azimuths, and free-field stimulation when the ipsilateral ear was occluded monaurally (coated with a thick layer of petroleum jelly, which effectively attenuated acoustic input to this ear). 2. The binaural interaction pattern of 98 IC neurons of northern leopard frogs (Rana pipiens pipiens) were evaluated; of these neurons, there were 34 EE and 64 EO neurons. The majority of IC neurons (92 of 98) showed some degree of binaural inhibition (i.e., showing diminished response when the ipsilateral and contralateral ears were stimulated simultaneously) whether they were designated as EE or EO; these IC neurons thus were classified as EE-I or EO-I. Neurons were classified as exhibiting strong inhibition if the ILD function showed a pronounced response decrement, i.e., a decrease of > or = 50% of the response to monaural stimulation of the contralateral ear. Those neurons that showed smaller response decrements (decrease was > or = 25% but < 50%) were designated as showing weak inhibition. Most of these EE-I and EO-I neurons (n = 68) showed strong binaural inhibition. 3. In agreement with results from our earlier studies, frequency threshold curves (FTCs) of IC neurons were altered by sound azimuth. Independent of binaural interaction pattern, most IC neurons (59 of 98) showed a narrowing of the FTC as sound direction was changed from contralateral 90 deg (c90 degrees) to ipsilateral 90 deg (i90 degrees). IC neurons that exhibited the largest direction-dependent changes in frequency selectivity were typically those that displayed stronger binaural inhibition. Occlusion of the ipsilateral ear, which reduced the strength of binaural inhibition by this ear, abolished direction-dependent frequency selectivity. 4. FTCs of IC neurons that exhibited little to moderate direction-dependent effects on frequency selectivity were associated typically with neurons that displayed weak binaural inhibition. Associated with this weak binaural inhibition, central neural responses under monaural occlusion also displayed only small effects; the FTCs were only slightly broader than those derived in the intact condition, and as before, the experimental manipulation resulted in abolishment of direction-dependent frequency selectivity. 5. In contrast to most IC neurons, which showed direction-dependent narrowing of the FTC, about one-third (34 of 98) of IC neurons studied showed a broadening of the FTC when sound direction was shifted to ipsilateral azimuths. Interestingly, for 90% of these 34 neurons, monaural occlusion resulted in narrowing of the bandwidth at each azimuth instead of broadening of the FTC bandwidth. We have evidence to suggest that this direction-dependent broadening is actually a consequence of a truncation or loss of the tip of the FTC derived at c90 degrees, which results from strong binaural inhibition. 6. To compare the frequency threshold tuning in response to monaural stimulation of each ear with free-field FTCs, we measured FTCs for each of the 34 EE neurons to independent contralateral and ipsilateral stimulation. FTCs derived from ipsilateral monaural stimulation were significantly narrower than those resulting from contralateral monaural stimulation, independent of a neuron's direction-dependent changes in frequency selectivity.
Acoustic Stimulation↗
Octadentate catecholamide ligands for Pu(IV) based on linear or preorganized molecular backbones.
Nine new octadentate ligands based on cyclic, spermine (3,4,3-LI), desferrioxamine (DFO), or H-shaped tetrakisamine (penten) molecular backbones were prepared containing catecholamide (CAM), carboxycatecholamide (CAM(C)), or terephthalamide (TAM) chelating units. Mice were injected intravenously with 239Pu(i.v.) citrate, treated with 30 mumol kg-1 of a ligand by intraperitoneal injection at 1 h or by gastric intubation at 3 min, and Pu retention in tissues and Pu transfer to excreta were measured at 24 h. Given by injection, three soluble ligands composed of MeTAM (3,4,3-LIMeTAM, DFO-MeTAM, H(2,2)-MeTAM) reduced Pu retention in the body to 27-28% of control compared with 32 and 37% of control obtained in mice similarly treated with 3,4,3-LICAM(C) or CaNa3-DTPA, respectively. The MeTAM ligands reduced Pu retention in the skeleton as much as an equimolar amount of CaNa3-DTPA, while Pu retention in the liver (on average, 16% of control) was significantly less than was obtained with CaNa3-DTPA (35% of control). Given orally, H(2,2)-MeTAM reduced Pu retention in the whole body to 58% of control compared with reductions to 62 and 94% of control achieved with 3,4,3-LICAM(C) or CaNa3-DTPA, respectively. Penten is both partially preorganized for metal binding and spatially suitable for encapsulation of actinide(IV), and ligands with the penten backbone are easier and less costly to prepare than those based on spermine or DFO. The biological results confirmed that penten is a suitable as well as practical structural backbone for new octadentate ligands. In agreement with the great stability of the ferric complex with MeTAM, as determined in vitro, the small, simple, soluble penten-based octadentate ligand, H(2,2)-MeTAM, was shown to be, overall, the most effective catecholamide ligand for enhancing Pu excretion. Either combined in H(2,2)-MeTAM or separately, the penten backbone and the MeTAM chelating unit are potentially useful additions to the set of backbones and binding units of multidentate ligands identified as effective for in vivo chelation of the actinides.
Administration, Oral↗
Neurohypophyseal and fluid homeostasis in transgenic rats expressing a tagged rat vasopressin prepropeptide in hypothalamic neurons.
We have developed a transgenic system that, for the first time, facilitates monitoring of the regulatory dynamics of a central peptidergic system from transcription of a neuropeptide gene to the storage and release of the mature secretory product. A rat vasopressin (VP) transgene (5-VCAT-3), the expression of which is restricted to hypothalamic vasopressinergic magnocellular neurons in rats, contains a sequence that, if translated, would place a unique hexadecapeptide (DRSAGYYGLFKDRKEK, abbreviated to DR-12-EK) at the C-terminus of the VP precursor. We have raised an antibody against this "tag" and, using immunohistochemistry, electron microscopy, RIA, and HPLC, have shown for the first time that a VP transgene RNA is translated into a protein product found, in a processed form, in secretory granules in the posterior pituitaries of transgenic rats. Disruption of the C-terminus of the VP precursor by the peptide tag is well tolerated and does not disrupt VP production or disturb salt and water balance. An osmotic stimulus increased hypothalamic DR-12-EK levels, but changes in posterior pituitary DR-12-EK levels were more complex. After 5 days of salt-loading, DR-12-EK levels fell, as would be expected if its release was coordinate with that of VP. However, after 10 days of salt-loading, posterior pituitary DR-12-EK levels increased, despite the lower level of VP. This probably reflects the greater response of the transgene to osmotic challenge at the RNA level, increasing the proportion of DR-12-EK-containing translation products transported to the posterior pituitary relative to those derived from the endogenous gene. The exaggerated response of the tagged transgene to osmotic challenge at both RNA and protein levels affords a new opportunity to study the regulatory dynamics of the VP system at the molecular level, but within the physiologically advantageous context of the intact animal.
Amino Acid Sequence↗
Mechanical strain induces constitutive and regulated secretion of glycosaminoglycans and proteoglycans in fetal lung cells.
We have previously shown that an intermittent strain regimen, which simulates fetal breathing movements, enhanced mixed fetal rat lung cell proliferation in organotypic culture. As glycosaminoglycans (GAGs) and proteoglycans (PGs) may modulate growth factor activities, we investigated the effect of intermittent strain on the formation and secretion of GAGs and PGs. Mechanical strain increased the incorporation of [3H]glucosamine and 35SO4 into GAGs and promoted the release of GAGs into the medium. The composition of the individual GAG molecules was not altered by strain. Mixed fetal lung cells subjected to strain secreted more [35S]biglycan into the medium than static controls but biglycan mRNA expression was not significantly altered. As mechanical strain primarily affected the secretion of GAGs and PGs, we then investigated which secretory pathways were stimulated by strain. Fetal lung cells secreted GAGs mainly through a constitutive (basal) pathway which was stimulated by strain. In contrast to static cultures, strain-induced constitutive secretion was partially blocked by the cytoskeletal disruptors colchicine and cytochalasin B, but not by the small G-protein inhibitors N-acetyl-S-farnesyl-L-cysteine and perillic acid. This result suggests that strain-induced constitutive export of GAGs depends on the functional integrity of the cytoskeleton. Strain also triggered the regulated secretion of GAGs. The strain-induced regulatory pathway in fetal lung cells was blocked by ionomycin, BAPTA/AM and gadolinium, suggesting that strain stimulated the regulatory pathway by inducing a rapid calcium influx via a stretch-activated ion channel. We conclude that mechanical strain of mixed fetal lung cells stimulates GAG and PG exocytosis via activation of both the regulated and constitutive pathways.
Animals↗
Establishment and evaluation of a new chemiluminescent enzyme immunoassay for carcinoembryonic antigen adapted to the fully automated ACCESS system.
We have established a new chemiluminescent enzyme immunoassay for carcinoembryonic antigen (CEA), designated ACCESS CEA, which is adapted to the fully automated ACCESS immunoassay analyzer. The assay is based on a one step sandwich-type method using two monoclonal antibodies, one of which is immobilized on micrometer-size paramagnetic particles and the other is conjugated to alkaline phosphatase. Ten microliters of calibrators or sera are incubated for 5 minutes at 37 degrees C with the particles and with the alkaline phosphatase conjugate. The particles are then magnetically separated and washed to remove unbound components. Time needed to obtain the first result is less than 15 minutes. The assay range was 0.04-1000 micrograms/l of CEA, and the possible high-dose hook effect was prevented at CEA concentrations up to 100000 micrograms/l in this working range. The coefficient of variation (CV) for intra-assay precision was 3.0 to 4.7%, and inter-assay CV was 3.4 to 5.6%. The sample carryover was less than 0.001%. The analytical recovery ranged from 98 to 104% and a dilution linearity was demonstrated. No interference was detected in any sample with levels up to 300 mg/l for bilirubin, 12000 mg/l for haemoglobin, 50000 mg/l for human serum albumin, 8500 mg/l for triacylglycerol, and 500000 IU/l for rheumatoid factor. The ACCESS CEA assay also showed very homogeneous reactivity with purified CEA preparations from different tumours and could discriminate CEA from four CEA-related normal antigens tested. Serum samples (n = 362) from patients with malignant or non-malignant disease, as well as from healthy individuals, were analyzed by the ACCESS CEA assay and by the established IMx CEA assay. The CEA values determined by the ACCESS CEA assay were in good agreement with those determined by the IMx CEA assay, and the ACCESS CEA assay significantly increased the sensitivity and specificity of tumour diagnosis as compared with the IMx CEA assay.
Carcinoembryonic Antigen↗
Cutaneous representations of the hand and other body parts in the cuneate nucleus of a primate, and some relationships to previously described cortical representations.
Dynamic properties of primate somatosensory maps are dependent on normal central adjacencies of cutaneous representations. The cuneate nucleus is an important brainstem processing center of cutaneous information. Surprisingly, there are no descriptions of functional representations of the skin in the primate cuneate nucleus; as a result, the relationships of functional representations at the brainstem level and other levels of the somatosensory neuraxis remain obscure. The present neurophysiological study indicates that the main cuneate nucleus of marmoset monkeys (Callithrix jacchus) contains organized representations of cutaneous inputs from the hand, forelimb, and adjacent body between the lateral face and proximal hindlimb. Inputs from the glabrous hand are represented continuously across transverse planes in the cuneate, whereas inputs from the hairy hand are represented discontinuously. Inputs from distal to proximal, and radial to ulnar, parts of the hand are mapped in an organized manner. At rostrocaudal levels where the cuneate nucleus is near its largest transverse area, the map of the hand is about 2600 times smaller than the hand skin area it represents. Cuneate representations of the forelimb and trunk are represented both medial and lateral to the hand representation, and interface with representations in the adjacent gracile and trigeminal nuclei. These findings provide a starting point for understanding functional representations of the skin in the cuneate nucleus of primates. Furthermore, they provide a basis for understanding relationships of cutaneous representations at different levels of the neuraxis. In this regard, comparisons of the present results to previously defined representations in the somatosensory (area 3b) cortex indicate that cuneate hand representations are several times smaller than cortical representations, and that there are similarities and differences in adjacencies of cuneate and cortical representations.
Animals↗
Biomechanical properties of peripheral nerves.
The biomechanical properties of peripheral nerves still are not completely understood or quantified. This is partly because of the nonhomogeneous nature of nerves and the variation in the proportions of the components of different nerves. The recognition and quantification of the in-situ stress and the viscoelastic behavior of nerves have been important stepping stones in understanding their mechanical behavior. The effects of stretch and compression on the vascular supply and conduction properties of normal animal nerves have been well studied. Similar studies in injured nerves will provide invaluable information for understanding the mechanics of nerve function and the prevention of stretch- and compression-related trauma.
Animals↗
[Clinical evaluation of cervical esophageal reconstruction after resection of thoracic esophageal carcinoma].
From Apr. 1979 to Dec. 1994, a total of 3,714 patients with thoracic esophageal carcinoma were surgically treated. As a standard operative procedure for thoracic esophageal cancer, cervical esophagogastrostomy was performed. While this operative procedure was rarely used (accounting for only 8.8% the treated cases) in early years, it has been recently carried out in the overwhelming majority of our patients (94.1%). This technic offers the advantages of resecting the lesions radically, dissecting the regional lymph nodes in both the neck and the mediastinum, reducing the incidence of postoperative complications and improving the quality of life after operation. In this paper the operative indication, approach and the surgical efficacy are discussed.
Adult↗
A new diarrhea pathogen: entero-adherent-invasive-toxigenic Escherichia coli.
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DNA, Bacterial↗
[Esterase isoenzyme of various types in rhizoma Gastrodiae].
By means of polyacrylamide gel slab electrophoresis, the esterase isoenzyme of various types in Gastrodia elata in different growing periods was studied and the relativity and difference in physiology and biochemistry were discussed. The result reveals that apparent variety of Rhizoma Gastrodiae is not decided by genetic factors.
Drugs, Chinese Herbal↗
[A study on AIDS-related knowledge, attitude and behavior in servicemen in China].
AIDS-related knowledge, attitude and behavior were studied in 1,058 servicemen in China with self-administered and anonymous questionnaires. Results showed 76.7% to 89.5% of the servicemen surveyed knew correctly the risk of AIDS and its route of transmission, but only 8.5% of them answered all the questions listed in the questionnaire correctly. Source of their knowledge about AIDS was mainly from newspapers, magazines and extracurricular books. Most of them thought they could have very little, or no chance to contract the illness. There were 74.0% of the servicemen eager to get knowledge about AIDS and 83.2% would like to accept relevant testing. And, 80.2% of them answered that they could put their behavior under control, or change their unhealthy one to prevent from the illness. It indicated that comprehensive and correct publicity and education could play an active role in the prevention of HIV infection.
Acquired Immunodeficiency Syndrome↗