Biomedical subjects
Publications and source records attributed to X Wan.
The achievement is described in five subheadings, viz. relevant people, relevant works, relevant events, academic relationship, and characteristic of stages. It is held that, the early development is not enough to demonstrate its significance and historical position, even less to show its development direction. It is essential to make further investigation.
OBJECTIVE: The effect of 5,7-dihydroxytryptamine (5,7-DHT) on distribution pattern of calcitonin gene-related peptide (CGRP) in different motoneuron pools was studied in rats. METHODS: Cholera toxin B subunit coupled with colloidal gold (CB-Au) retrograde labeling combined with CGRP immunocytochemistry technique was mainly used. RESULTS: In control group, there was a different distribution pattern of CGRP-LI content in soleus motoneuron (SOL-Mn) and extensor digitorum longus motoneuron (EDL-Mn) pools. SOL-Mn pools had a higher ratio of neurons lacking CGRP-LI/weak CGRP-LI and a lower proportion of strongly CGRP-LI labeled ones. Comparing with control, there was a marked shift to increasing of CGRP-LI content in SOL-Mn pool and slight decrease in EDL-Mn pools 14 days after 5,7-DHT. All the SOL-Mns were CGRP-LI positive and the ratio of CGRP-LI strongly positive Mns significantly increased (P < 0.001) while 5,7-DHT did not increase the ratio of CGRP-LI strongly positive Mn in EDL-Mn pool. CONCLUSIONS: Except muscular motor activity, the different distribution pattern of CGRP-LI content in SOL-Mn and EDL-Mn pools is related to different 5-HT inputs. SOL-Mns may receive more 5-HT inputs.
Effects of root zone temperature on growth, shoot water relations, and root water flow were studied in 1-year-old aspen (Populus tremuloides Michx.) seedlings. Seedlings were grown in solution culture and exposed to day/night air temperatures of 22/16 degrees C and solution culture temperatures of 5, 10, or 20 degrees C for 28 days after bud flush. Compared with root growth at 20 degrees C, root growth was completely inhibited at 5 degrees C and inhibited by 97% at 10 degrees C. The 5 and 10 degrees C treatments severely reduced shoot growth, leaf size, and total leaf area. Root water flow was inhibited by the 5 and 10 degrees C treatments. However, when seedlings were grown for 28 days at 5 degrees C and root water flow was measured at 20 degrees C, there was an increase in flow rate. This increase in root water flow was similar in magnitude to the decrease in root water flow observed when seedlings were grown for 28 days at 20 degrees C and root water flow was measured at 5 degrees C. Reduced root water flow of seedlings grown at 5 and 10 degrees C resulted in decreased stomatal conductance, net assimilation, and shoot water potentials. Root water flow was positively correlated with leaf size, total leaf area, shoot length, and new root growth. Transferring seedlings from 5 to 20 degrees C for 24 h significantly increased root water flow, shoot water potential, and net photosynthesis, whereas transferring seedlings from 10 to 20 degrees C resulted in only a slightly increased shoot water potential. Transferring seedlings from 20 to 5 degrees C greatly reduced root water flow, stomatal conductance, and net photosynthesis, whereas shoot water potential decreased only slightly.
Large-conductance Ca2+-dependent K+ channels (KCa), which are abundant on the sarcolemma of vascular myocytes, provide negative feedback via membrane hyperpolarization that limits Ca2+ entry through L-type Ca2+ channels (ICaL). We hypothesize that local accumulation of subsarcolemmal Ca2+ during ICaL openings amplifies this feedback. Our goal was to demonstrate that Ca2+ entry through voltage-gated ICaL channels can stimulate adjacent KCa channels by a localized interaction in enzymatically isolated rabbit coronary arterial myocytes voltage clamped in whole-cell or in cell-attached patch clamp mode. During slow-voltage-ramp protocols, we identified an outward KCa current that is activated by a subsarcolemmal Ca2+ pool dissociated from bulk cytosolic Ca2+ pool (measured with indo 1) and is dependent on L-type Ca2+ channel activity. Transient activation of unitary KCa channels in cell-attached patches could be detected during long step depolarizations to +40 mV (holding potential, -40 mV; 219 pS in near-symmetrical K+). This local interaction between the channels required the presence of Ca2+ in the pipette solution, was enhanced by the ICaL agonist Bay K 8644, and persisted after impairment of the sarcoplasmic reticulum by incubation with 10 micromol/L ryanodine and 30 micromol/L cyclopiazonic acid for at least 60 minutes. Furthermore, we provide the first direct evidence of simultaneous openings of single KCa (67 pS) and ICaL (3.9 pS) channels in near-physiological conditions, near resting membrane potential. Our data imply a novel sensitive mechanism for regulating resting membrane potential and tone in vascular smooth muscle.
OBJECTIVES: To determine whether the incidence of cancers other than the AIDS-defining cancers is increased in people with AIDS, and to determine if cancer incidence increases with time, a surrogate marker of declining immune function. DESIGN: Register-based retrospective cohort study in New South Wales, Australia. Age-, sex-, and period-adjusted standardized incidence ratios (SIR) were calculated for individual cancers occurring in 1980-1993 in people with AIDS registered before 1996. RESULTS: During the study period, 3616 people were registered with AIDS; 716 cases of AIDS-defining cancer and 62 cases of non-AIDS-defining cancer were identified. People with AIDS had a significantly increased incidence of Hodgkin's disease [SIR 18.3; 95% confidence interval (CI) 8.39-34.8], multiple myeloma (SIR 12.1; 95% CI 2.50-35.4), leukaemia (SIR 5.76; 95% CI 1.57-14.7), lip cancer (SIR 5.94; 95% CI 1.92-13.8) and lung cancer (SIR 3.80; 95% CI 1.39-8.29). The incidence of Hodgkin's disease increased significantly around the time of AIDS diagnosis (P = 0.008 for trend with time), suggesting an association with immunodeficiency. CONCLUSIONS: This study provides strong support for the hypothesis that Hodgkin's disease is an AIDS-associated condition. There was an increased incidence of several other forms of cancer, some of which are known to occur at increased rates in transplant recipients who have received immunosuppressive therapy. Improved survival in people with HIV infection may lead to increases in the number that develop these forms of cancer.
This paper reports the first in vivo NMR image of the distribution of NO using the "MRI spin-trapping" technique. NO was complexed with the Fe(II)-chelate spin trap, N-methyl-D-glucamine dithiocarbamate (MGD), verified as (MGD)(2)-Fe(II)-NO by EPR, and the radical distribution was "visualized" by MR images. In rats, the (MGD)(2)-Fe(II)-NO complex was concentrated in the liver displaying significantly enhanced contrast in the vascular structure such as hepatic vein and inferior vena cava. Nitric oxide synthase was verified as the source of NO in rats with septic shock by pre-administration of the competitive inhibitor N-monomethyl-L-arginine, resulting in reduced enhancement. The NO complex was more stable in vivo and a more effective MRI contrast agent than other stable nitrogen containing radicals, such as nitroxides. The MRI spin-trapping method should be a powerful tool for visualizing spatial distributions of free radicals in pathologic organs and tissues when combined with the appropriate radical complexing agent, such as (MGD)(2)-Fe(II) used in these studies. Magn Reson Med 42:235-239, 1999.
HgCl(2) (0.1 mM) reduced pressure-induced water flux and root hydraulic conductivity in the roots of 1-year-old aspen (Populus tremuloides Michx.) seedlings by about 50%. The inhibition was reversed with 50 mM mercaptoethanol. Mercurial treatment reduced the activation energy of water transport in the roots from 10.82 +/- 0.700 kcal mol(-1) to 6.67 +/- 0.193 kcal mol(-1) when measured over the 4 degrees C to 25 degrees C temperature range. An increase in rhodamine B concentration in the xylem sap of mercury-treated roots suggested a decrease in the symplastic transport of water. However, the apoplastic pathway in both control and mercury-treated roots constituted only a small fraction of the total root water transport. Electrical conductivity and osmotic potentials of the expressed xylem sap suggested that 0.1 mM HgCl(2) and temperature changes over the 4 degrees C to 25 degrees C range did not induce cell membrane leakage. The 0.1 mM HgCl(2) solution applied as a root drench severely reduced stomatal conductance in intact plants, and this reduction was partly reversed by 50 mM mercaptoethanol. In excised shoots, 0.1 mM HgCl(2) did not affect stomatal conductance, suggesting that the signal that triggered stomatal closure originated in the roots. We suggest that mercury-sensitive processes in aspen roots play a significant role in regulating plant water balance by their effects on root hydraulic conductivity.
Human herpesvirus 8 (HHV-8) has been associated with classical, endemic (African), and AIDS-related Kaposi's sarcoma (KS), body cavity-based primary effusion lymphomas, and multicentric Castleman's disease (MCD). HHV-8 encodes a functional homologue of interleukin-6 (IL-6), a cytokine that promotes the growth of KS and myeloma cells and is found at elevated levels in MCD lesions and patient sera. We have previously reported that the viral IL-6 (vIL-6) gene product can support the growth of the IL-6-dependent murine hybridoma cell line, B9, and that the gp80 (IL-6 receptor [IL-6R]) component of the IL-6 receptor-signal transducer (gp180) complex plays a role in mediating this activity. However, it has been shown by others that vIL-6 can function in human cells independently of IL-6R. Here we have extended our functional studies of vIL-6 by identifying transcription factors and pathways used in human Hep3B cells, investigating the utilization of gp130 and IL-6R by vIL-6, and undertaking mutational analyses of vIL-6 and gp130. The data presented here establish that vIL-6, in common with its endogenous counterparts, can mediate signal transduction through gp130 and activate multiple transcription factors, map residues within the vIL-6 protein that are and are not important for vIL-6 signalling, and identify a gp130 mutant that is nonfunctional with respect to vIL-6 signalling in the absence of IL-6R but that retains the ability to mediate vIL-6 and human IL-6 (hIL-6) signal transduction when IL-6R is coexpressed. The data presented demonstrate functional and mechanistic similarities between vIL-6 and endogenous IL-6 proteins but also highlight differences in the structural and receptor-binding properties of vIL-6 relative to its human counterpart.
Infection with Kaposi's sarcoma (KS)-associated herpesvirus (KSHV) or human herpesvirus 8 (HHV8) is common in certain parts of Africa, the Middle East, and the Mediterranean, but is rare elsewhere, except in AIDS patients. Nevertheless, HHV8 DNA is found consistently in nearly all classical, endemic, transplant and AIDS-associated KS lesions as well as in some rare AIDS-associated lymphomas. The concept that HHV8 genomes fall into several distinct subgroups has been confirmed and refined by PCR DNA sequence analysis of the ORF-K1 gene encoding a highly variable glycoprotein related to the immunoglobulin receptor family that maps at the extreme left-hand end of the HHV-8 genome. Among more than 60 different tumor samples from the United States, central Africa, Saudi Arabia, Taiwan, and New Zealand, amino acid substitutions were found at a total of 62% of the 289 amino acid positions. These variations defined four major subtypes and 13 distinct variants or clades similar to those found for the HIV ENV protein. The B and D subtype ORF-K1 proteins differ from the A and C subtypes by 30 and 24%, respectively, whereas A and C differ from each other by 15%. In all cases tested, multiple samples from the same patient were identical. Examples of the B subtype were found almost exclusively in KS patients from Africa or of African heritage, whereas the rare D subtypes were found only in KS patients of Pacific Island heritage. In contrast, C subtypes were found predominantly in classic KS and in iatrogenic and AIDS KS in the Middle East and Asia, whereas U.S. AIDS KS samples were primarily A1, A4, and C3 variants. We conclude that this unusually high diversity, in which 85% of the nucleotide changes lead to amino acid changes, reflects some unknown powerful biological selection process that has been acting preferentially on this early lytic cycle membrane signalling protein. Two distinct levels of ORF-K1 variability are recognizable. Subtype-specific variability indicative of long-term evolutionary divergence is both spread throughout the protein as well as concentrated within two 40-amino-acid extracellular domain variable regions (VR1 and VR2), whereas intratypic variability localizes predominantly within a single 25-amino-acid hypervariable Cys bridge loop and apparently represents much more recent changes that have occurred even within specific clades. In contrast, numerous extracellular domain glycosylation sites and Cys bridge residues as well as the ITAM motif in the cytoplasmic domain are fully conserved. Overall, we suggest that rather than being a newly acquired human pathogen, HHV8 is an ancient human virus that is preferentially transmitted in a familial fashion and is difficult to transmit horizontally in the absence of immunosuppression. The division into the four major HHV8 subgroups is probably the result of isolation and founder effects associated with the history of migration of modern human populations out of Africa over the past 35,000 to 60,000 years.
Mechanosensitive (MS) channels, ones whose open probability varies with membrane tension in patch recordings, are diverse and ubiquitous, yet many are remarkably insensitive to mechanical stimuli in situ. Failure to elicit mechanocurrents from cells with abundant MS channels suggests that, in situ, the channels are protected from mechanical stimuli. To establish what conditions affect MS channel gating, we monitored Lymnaea neuron stretch-activated K (SAK) channels in cell-attached patches after diverse treatments. Mechanosensitivity was gauged by rapidity of onset and extent of channel activation during a step pressure applied to a "naive" patch. The following treatments enhanced mechanosensitivity: actin depolymerization (cytochalasin B), N-ethylmaleimide, an inhibitor of ATPases including myosin, elevated Ca (using A-23187), and osmotic swelling (acutely and after 24 h). Osmotic shrinking decreased mechanosensitivity. A unifying interpretation is that traumatized cortical cytoskeleton cannot prevent transmission of mechanical stimuli to plasma membrane channels. Mechanoprotection and capricious mechanosensitivity are impediments to cloning efforts with MS channels. We demonstrate a potpourri of endogenous MS currents from L-M(TK-) fibroblasts; others had reported these cells to be MS current null and hence to be suitable for expressing putative MS channels.
OBJECTIVE: The authors investigated the links between depression, cardiac disease, and microcirculatory cerebral blood flow (CBF). METHOD: A magnetic resonance imaging technique based on arterial spin tagging was used to estimate microcirculatory CBF in depressed (N = 5) and comparison (N = 14) elderly subjects with coronary artery disease. Signal intensity ratios corresponding to relative microcirculatory CBF were calculated for four regions on two axial images through the upper and lower halves of the lateral ventricles. RESULTS: On the superior image, estimates of microcirculatory CBF were statistically significantly lower on the left side in the depressed subjects than in the nondepressed group. When the ratios in the superior and inferior images were averaged, the depressed subjects had lower values for both left periventricular regions of interest and the parietal region. CONCLUSIONS: Despite the small study group and indirect estimates of blood flow, these preliminary findings suggest that a relative cerebral hypoperfusion may underlie depression in elderly cardiac patients.
Human rabies is a fatal encephalomyelitis. After the development of the central nervous system infection, there is centrifugal spread of the rabies virus to extraneural (systemic) organs. With histochemical staining and localization of rabies virus antigen (RVA) with immunoperoxidase staining, we have examined tissue sections of organs from 14 postmortem pediatric and adult cases of human rabies acquired in Mexico and the People's Republic of China. RVA was found in nerve plexuses in multiple organs, including the gastrointestinal tract. RVA was observed in muscle fibers of the heart, tongue, and larynx. RVA frequently was observed in the adrenal medulla with an associated inflammatory reaction. Minor salivary glands of the tongue contained RVA and major salivary glands showed RVA in plexuses, but not in either acini or ducts. Epithelial cells of the tongue and taste buds were occasionally infected. RVA was observed in hair follicles of the skin and rarely in pancreatic islets. The infection of extraneural organs was sometimes, but not always, associated with an inflammatory reaction. These findings indicate that centrifugal spread of rabies virus to extraneural organs occurs frequently in human rabies.
OBJECTIVE: To study the efficiency of radioimmunodetection (RID) to locate the loci of trophoblastic disease. METHOD: 24 RIDs were performed with 131I labeled mouse anti-hCG monoclonal antibodies on 21 patients with trophoblastic disease. RESULTS: Of 24 RIDs performed, 13 were positive, including one false positive; 11 were negative, including two false negative. The sensitivity of RID was 85.7%, the specificity was 90.0%, the accuracy was 87.5%. In 8 patients who underwent operations after RID, the findings of RID were in accordance with the pathologic and immunohistologic findings. CONCLUSIONS: RID is an efficient imaging method for trophoblastic disease. In some cases, RID showed its value as a functional diagnostic method.
OBJECTIVE: To study the efficiency of radioimmunodetection to locate xenograft of human trophoblastic cancer in nude mouse. METHODS: Radioimmunodetection was performed with a cocktail of 131I-labeled mouse anti-hCG monoclonal antibodies to image xenogaft of human trophoblastic cancer in nude mice. Normal mouse IgG used to treat mice bearing trophoblastic cancer xenograft was used as control. Radioactivity in different tissues was measured and the tumor/non-tumor(T/NT) ratio was calculated. RESULTS: The accumulation of radioactivity in the xenograft could be recognized as early as 24 hours after the injection of the radiolabeled anti-hCG antibodies. Radioactivity accumulation became increasingly evident with time. At 72-96 hours after injection of the radiolabled antibodies, the xenograft could be clearly shown. The minimal size of the xenograft with demonstrable radioactively was 0.8 cm in diameter. The T/NT ratio increased with time and was obviously higher than that in mice treated with normal mouse IgG. CONCLUSION: Radioimmunodetection can efficiently locate human trophoblastic cancer xenograft in nude mice.
OBJECTIVE: To assess the severity and temporal profile of remote effects of botulinum toxin type A, BTX-A (Botox from Allergan Inc, USA and CBTX-A made by Lanzhou Biological Products Institute, China) injected locally on neuromuscular junction. METHODS: Patients had enrolled in a prospective study for their movement disorders, 18 cases with Botox and 22 cases with CBTX-A were studied. Single fiber electromyography (SFEMG) in the extensor digitorum communis muscle or tibialis anterior muscle was performed before and 2-3 weeks, 5-8 weeks, 4-5 months after injection of Botox or CBTX-A. RESULTS: It was measured totally 119 times. Significant increase of jitter was demonstrated 2-3 weeks after injections in both groups and MCD was in direct proportion to dose of injections. Fiber density value increased at the same time or later and lasted until 4-5 months after injections. CONCLUSIONS: Subclinical effects on neuromuscular transmission of remote uninjected muscles after injections of Botox and CBTX-A are demonstrated, which indicates that the toxin spread distantly from the site of injection. SFEMG is valuable for studying the pathogenesis of the remote effects of BTX-A and for avoiding reinjection too frequently.
OBJECTIVE: In order to investigate how widespread the activated regions induced by an olfactory stimulus throughout the central nervous system (CNS), c-fos expressions in CNS of the rat observed, which is known as a combined morphologically and functionally probe. METHODS: Rats were stimulated by iso-amyl acetate for about 10 times, then one hour later sacrificed with perfusion of fixatives. After ABC immunocytochemi cal staining with anti-c-fos polyclonal antiserum, the c-Fos protein labelling areas on sections of the brain were observed. RESULTS: The results showed that the labelling areas were estremely widespread throughout the brain and cervical segments of the spinal cord in the rat, expecially much more in the areas above the level of the pons. Nearly all neuronal structures in the limbic system were labeled in addition to structures of the olfactory pathways, suggesting there were neuronal activities in multiple neural circuits, which may be associated with emotional, somatic and visceral responses to the olfactory stimulus. Next, many brain areas which were associated with mechanisms of attention and central state regulation were widely labeled. Unexpected heavy labellings in deep layers of the superior colliculus, inferior colliculus and pontine nuclei were presumably relevant to integrating activity between sensations and motions. CONCLUSIONS: The present study indicated that a specific olfactory stimulus did induce widespread activities of so-called pan-brain networks within the central nervous system.
Telomerase activity is found in almost all carcinoma cells but not in most somatic cells, suggesting that telomerase is an excellent target for cancer therapy. We designed hammerhead ribozymes against human telomerase RNA and studied their possible use as a tool for cancer therapy. Three ribozymes targeting the 3' end of the GUC sequence at 33-35 (the template region), 168-170, and 313-315 from the 5' end of telomerase RNA were designed. In a cell-free system, these three hammerhead ribozymes efficiently cleaved the RNA substrate. When these ribozyme RNAs were introduced into Ishikawa cells, which are endometrial carcinoma cells, only a ribozyme targeting the RNA template region could diminish the telomerase activity. Next we subcloned the ribozyme sequence into an expression vector and introduced this into AN3CA cells, which are endometrial carcinoma cells. The clones that were obtained showed reduced telomerase activity and telomerase RNA with expression of the ribozyme. These data suggest that the ribozyme against the RNA template region is a good tool to repress telomerase activity in cancer cells.
When neurons undergo dramatic shape and volume changes, how is surface area adjusted appropriately? The membrane tension hypothesis-namely that high tensions favor recruitment of membrane to the surface whereas low tensions favor retrieval-provides a simple conceptual framework for surface area homeostasis. With membrane tension and area in a feedback loop, tension extremes may be averted even during excessive mechanical load variations. We tested this by measuring apparent membrane tension of swelling and shrinking Lymnaea neurons. With hypotonic medium (50%), tension that was calculated from membrane tether forces increased from 0.04 to as much as 0.4 mN/m, although at steady state, swollen-cell tension (0. 12 mN/m) exceeded controls only threefold. On reshrinking in isotonic medium, tension reduced to 0.02 mN/m, and at the substratum, membrane invaginated, creating transient vacuole-like dilations. Swelling increased membrane tension with or without BAPTA chelating cytoplasmic Ca2+, but with BAPTA, unmeasurably large (although not lytic) tension surges occurred in approximately two-thirds of neurons. Furthermore, in unarborized neurons voltage-clamped by perforated-patch in 50% medium, membrane capacitance increased 8%, which is indicative of increasing membrane area. The relatively damped swelling-tension responses of Lymnaea neurons (no BAPTA) were consistent with feedback regulation. BAPTA did not alter resting membrane tension, but the large surges during swelling of BAPTA-loaded neurons demonstrated that 50% medium was inherently treacherous and that tension regulation was impaired by subnormal cytoplasmic [Ca2+]. However, neurons did survive tension surges in the absence of Ca2+ signaling. The mechanism to avoid high-tension rupture may be the direct tension-driven recruitment of membrane stores.