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Biomedical subjects

X Wan

Publications and source records attributed to X Wan.

At least 73 records · Page 4Linked to original sources
PubMed1998

Magnetic resonance thermometry during hyperthermia for human high-grade sarcoma.

PURPOSE: To determine the feasibility of measuring temperature noninvasively with magnetic resonance imaging during hyperthermia treatment of human tumors. METHODS: The proton chemical shift detected using phase-difference magnetic resonance imaging (MRI) was used to measure temperature in phantoms and human tumors during treatment with hyperthermia. Four adult patients having high-grade primary sarcoma tumors of the lower leg received 5 hyperthermia treatments in the MR scanner using an MRI-compatible radiofrequency heating applicator. Prior to each treatment, an average of 3 fiberoptic temperature probes were invasively placed into the tumor (or phantom). Hyperthermia was applied concurrent with MR thermometry. Following completion of the treatment, regions of interest (ROI) were defined on MR phase images at each temperature probe location, in bone marrow, and in gel standards placed outside the heated region. The median phase difference (compared to pretreatment baseline images) was calculated for each ROI. This phase difference was corrected for phase drift observed in standards and bone marrow. The observed phase difference, with and without corrections, was correlated with the fiberoptic temperature measurements. RESULTS: The phase difference observed with MRI was found to correlate with temperature. Phantom measurements demonstrated a linear regression coefficient of 4.70 degrees phase difference per degree Celsius, with an R2 = 0.998. After human images with artifact were excluded, the linear regression demonstrated a correlation coefficient of 5.5 degrees phase difference per degree Celsius, with an R2 = 0.84. In both phantom and human treatments, temperature measured via corrected phase difference closely tracked measurements obtained with fiberoptic probes during the hyperthermia treatments. CONCLUSIONS: Proton chemical shift imaging with current MRI and hyperthermia technology can be used to monitor and control temperature during treatment of large tumors in the distal lower extremity.

Adult↗
PubMed1998

Simultaneous multislice acquisition with arterial-flow tagging (SMART) using echo planar imaging (EPI).

Arterial spin tagging techniques have been used to image tissue perfusion in MR without contrast injection or ionizing radiation. Currently, spin tagging studies are performed primarily using single-slice imaging sequences, which are time consuming. This note reports a multislice echo-planar arterial spin tagging technique (Simultaneous Multislice Acquisition with aRterial-flow Tagging, or "SMART"). Multiband RF encoding (Hadamard) is used to provide simultaneous multislice acquisition capability for spin tagging techniques (such as echo planar imaging signal targeting with alternating radio frequency and flow-sensitive alternative inversion recovery). The method is illustrated with a two-slice pulse sequence that was implemented using the FAIR technique to generate two perfusion weighted images simultaneously. Compared with single-slice sequences, this two-slice sequence provided similar image quality, signal-to-noise ratio, and twice the spatial coverage compared with the single-slice technique within the same scan time.

Blood Flow Velocity↗
PubMed1998

Regional differences in the delayed rectifier current (IKr and IKs) contribute to the differences in action potential duration in basal left ventricular myocytes in guinea-pig.

OBJECTIVE: To compare the properties of single myocytes isolated from different layers of the basal region of the left ventricle and to test the hypothesis that differences in the delayed rectifier current (IK) contribute to regional differences in action potential duration. METHODS: Myocytes were isolated from basal sub-endocardial, mid-myocardial and sub-epicardial layers of the guinea-pig left ventricle. Membrane voltage and current were measured using the switch-clamp technique. RESULTS: Mean action potential duration measured at 90% repolarisation (APD90) was longer in sub-endocardial myocytes than in mid-myocardial and sub-epicardial myocytes [APD90 ms at 0.2 Hz: sub-endocardial 292 +/- 12 (n = 40), mid-myocardial 243 +/- 8 (n = 42) and sub-epicardial 227 +/- 9 (n = 36), P < 0.001, analysis of variance (ANOVA)]. The APD-rate relationship (stimulation frequencies 2, 1, 0.2 and 0.017 Hz) was steeper in sub-endocardial than in mid-myocardial or sub-epicardial myocytes (P < 0.001, ANOVA). The density of IK was greater in mid-myocardial (4.05 +/- 0.09 pA pF-1) and sub-epicardial (3.90 +/- 0.41 pA pF-1) than in sub-endocardial myocytes (2.74 +/- 0.27 pA pF-1, P < 0.01 ANOVA). The rapidly-activating (IKr) and slowly-activating (IKs) components of IK were significantly smaller in sub-endocardial than in mid-myocardial or sub-epicardial myocytes. D,L-Sotalol-induced prolongation of APD90 was similar in the three regions studied. CONCLUSIONS: There are significant transmural gradients in the electrophysiological properties of myocytes isolated from the base of the left ventricular free wall in guinea-pig. Sub-endocardial myocytes had a longer APD90 attributable in part to a significantly smaller IK density. We have been unable to identify M cells in the guinea-pig left ventricular free wall.

Action Potentials↗
PubMed1998

Novel organizational features, captured cellular genes, and strain variability within the genome of KSHV/HHV8.

Strong serologic and molecular probe correlations indicate that the newly discovered gamma herpesvirus KSHV or HHV8 is the likely etiologic agent of all forms of Kaposi's sarcoma as well as BCBL/PEL and MCD in patients with acquired immunodeficiency syndrome (AIDS). Two large segments of HHV8 DNA from an AIDS-associated BCBL tumor covering genomic positions 0-52 kilobase [kb] and 108-140 kb have been cloned, mapped, and partially sequenced. Our studies have focused on novel viral proteins encoded within a 13-kb divergent locus (DL-B) by nine captured homologues of cellular genes, including vIL-6, vDHFR, vTS, vBcl-2, three C-C beta chemokines (vMIP-1A, vMIP-1B, and vBCK), and two LAP/PHD subclass zinc finger proteins (IE1A and IE1B). The HHV-8 vIL-6, vDHFR, vTS, and vBcl-2 proteins have all been shown to be active in a variety of appropriate functional assays, and transcripts from vIL-6, vMIP-1B, vIE1-A, vIE1-B, and vDHFR genes are all expressed as abundant single messenger RNA species after butyrate or phorbol ester (TPA) induction of the lytic cycle in HHV8-positive BCBL cell lines. All of these genes lie within a divergent transcriptional domain that contains a single central enhancer and associated untranslated leader region plus seven distinct proximal promoters, some of which are negatively regulated through AP-1 and ZRE motifs by the EBV ZTA transactivator. This region also encompasses a predicted complex oriLyt domain of 1050 bp that is duplicated in inverted orientation adjacent to the T0.7 latency RNA in another large divergent locus (DL-E). We have previously described three distinct subtypes of the HHV8 genome that differ by 1.0%-1.5% at the nucleotide level within the ORF26 and ORF75 genes. Certain strains or clades appear to have preferential geographic distributions, but it is not known as yet whether there are any specific disease associations. Interestingly, the A, B, and C subtypes of HHV-8 also proved to differ dramatically in coding content at both the extreme left and right ends of the unique segment of the genome as well as in the positions of the junctions with the terminal repeats. On the left-hand side, the receptor-like ORF-K1 protein is highly variable with A-strain subtypes displaying 15% amino acid differences from C strains and up to 30% differences from B strains. On the right-hand side, two unrelated alternative types of the putative multiple membrane spanning ORF-K15 protein are found.

Amino Acid Sequence↗
PubMed1998

[Comparison of Botox and a Chinese type a botulinum toxin in cervical dystonia].

OBJECTIVE: To confirm and compare the therapeutic efficacy of a Chinese type A botulinum toxin (CBTX-A, made by Lanzhou Biological Products Institute) and Botox (from Allergan Inc.) for cervical dystonia. METHODS: Prospective open study over 3 years for cervical dystonia was analyzed. We treated 113 patients with medically intractable cervical dystonia in two groups during 1993-1996, 32 patients with Botox and 81 with CBTX-A, with the age, durations and severity (Tsui's scale) matched. Some patients were injected under EMG guidance if necessary. The patients enrolled were followed up for 6-42 months. RESULTS: Considerable improvement of symptoms for the CD patients was observed with either Botox or CBTX-A. The Tsui scores showed a significant reduction after BTX-A injections. There were no significant differences in the clinical effects of two preparations, including the latency of response, maximal benefit, and duration of improvement. The patients' subjective assessments were similar. But the requested dose of Chinese preparation which produced the similar effects was statistically higher than that of Botox. Skin rash appeared within a few days after injections in 3 cases of CBTX-A group, but no one in Botox group. No statistical differences were noted in the other adverse reaction between them. CONCLUSION: The injections of two kinds of preparation both were simple and effective for the patients with cervical dystonia. Chinese preparation is a little less powerful but much cheaper than Botox.

Adolescent↗
PubMed1998

[Neurotoxicity of antibody against motoneuron on cultured rat cortical neurons].

OBJECTIVE: In order to determine the role of antibody against motoneuron in the process of neuronal death. METHODS: Cultured rat cortical neurons growing in serum-free medium, were employed to observe the effects of antibody against motoneuron (anti-SMN) on the survival of these cultured neurons. RESULTS: (1) Exposure of the cultures in serum-free medium to anti-SMN with dilution of 1:50 results in death of 31%-41% of neurons for 24 hours incubation, 50%-67% for 48 hours and above 90% after 72 hours. The neurotoxicity induced by anti-SMN was accompanied by concentration-dependent release of lactate dehydrogenase into the culture medium. Cultures exposed to normal rat IgG as controls exhibited no such sign. (2) The cultured neurons exposed to anti-SMN (1:200) expressed markedly higher levels of immunoreactive Calbindin-D28k especially after 48 hours incubation with it. There was a reduction in the number of acetylcholinesterase-positive neurons compared to the normal control. CONCLUSIONS: The anti-SMN could directly initiate the process of cortical neuronal death and this effect was independent of complement. The alteration of Calbindin-D28k immunoreactivity implied that calcium may be involved in the neurotoxicity induced by anti-SMN.

Acetylcholinesterase↗
PubMed1998

[Spinal segment distribution of neural innervation related to houhai acupoint and compared with zusanli and dazhui acupoints in domestic chicken].

OBJECTIVE: The aim of this study was to demonstrate the spinal segmental innervation of Houhai, Dazhui and Zusanli acupoints in domestic chicken. METHODS: The horseradish peroxidase conjugated cholera toxin B subunit (CB-HRP) was injected into the regions of the three acupoints namely, Houhai Dazhui and Zusanli respectively in separate groups of chicken. The frozen sections of spinal cord and dorsal ganglia were prepare for labelling using TMB as a chromogen. RESULTS: (1) In Houhai group the anterograde transganlionic labelling terminals were densely distributed in the dorsal horn and dorsal commissure nucleus. The moto-neurons in ventral horn labelled retrogradely appeared fine arborization of dendrites. There were labelled cell bodies in the dorsal region of the ventral horn (lamina VII) or dorsal commissure nucleus. (2) In Dazhui group, the bundles of labelled fibers presented from laminea I and II to IX in the caudal cervical enlargements and two upper thoracic segments. The labelled motoneurons were shown in medial and lateral groups. The most numourous of labelled ganglionic cells appeared in this group. (3) The labelling sensory ganglionic neurons and their terminals in spinal cord related Zusanli acupoint were overlaped with those related Houhai acupoint. The largest numbers of the labelled ventral motoneurons occured in the Zusanli group. CONCLUSIONS: The results demontrated the patterns of segmental innervation corresponding respectively to Houhai, Dazhui, and Zusanli acupoints. The anterograde afferent labelling terminals and interrelationship of the dendritic arborization of retrograde labelling motoneurons (somatic or visceral) provided neuroanatomical evidences for the innervation of the acupoints.

Acupuncture Points↗
PubMed1998

[Expression of IL-1 mRNA and its correlation with astrocytes and NOS-positive neurons in rat spinal cord following sciatic nerve injury].

OBJECTIVE: To study expression of Interleukin 1 (IL-1) and its correlation with astrocytes and nitric-oxide synthase (NOS)-positive neurons in rat spinal cord following sciatic nerve transection. METHODS: Using RT-PCR and immunohistochemistry methods. RESULTS: The experiments showed that IL-1 expression appeared with a low frequency at 3 days after the axontomy, while it could be markedly detectable on post-lesioned day 7 and 14. In normal controls and the spinal fragments without being involved in the injury, no signal of IL-1 mRNA expression was detected with the same condition. At 7 days after nerve injury, the lesioned side of spinal cord began to show strong glial fibrillary acidic protein (GFAP) immunoreactive astrocytes and induction of NOS in the motoneurons that are normally NOS-negative. Up to 21 days after operation, GFAP staining showed star-shaped astrocytes closely resembling the typical appearance of fibrous astrocytes and GFAP-immunoreactive profiles were often seen surrounding NOS-positive neurons. Analysis of the time course of IL-1 mRNA expression, appearance of NOS-positive neurons and changes of reactive astrocytes suggested a close relationship between them. CONCLUSIONS: IL-1, NO might function as important mediators between injured motoneurons and astrocytes.

Animals↗
PubMed1998

[Studies on the functional anatomy of Golgi-phobic dendrites of spinal motoneurons in rats--different dendroarchitectures of the motoneurons to slow muscle and fast one].

OBJECTIVE: The functional anatomy of Golgi-phobic dendrites (GBD) of spinal motoneurons (Mn) in rats was studied from their postnatal development. METHODS: Cholera toxin B subunit conjugated with horseradish peroxidase (CB-HRP) retrograde labelling method was mainly used. RESULTS: In the extensor digitorum longus Mn pool (EDL-Mn) GBD gradually decrease during development and are only a few in adults. The related value of the surface density of the white matter dendrites, most of them are GBD, of the soleus Mn pool (SOL-Mn) is nearly double than that of EDL-Mn. CONCLUSIONS: GBD of motoneurons might be related to their action patterns, especially the tonic action of slow muscle, such as the soleus. The hypotheis of dual circuits in motor control, the paralateral circuit on GBD regulates control of tonic action and the core circuit on Golgi-philic dendrites (GLD) and somata regulates phasic action, such as on EDL-Mn, has been further enhanced.

Animals↗
PubMed1998

[Genetic characterization of an avian influenza A (H5N1) virus isolated from a sick goose in China].

Genetic analysis of viral HA gene showed that there were 22 nucleotide differences in HA gene between goose and human H5N1 viruses. The sequence analysis of amino acid on viral protein molecules indicated that there were 7 and 9 position differences between goose and human, chicken H5N1 viruses, respectively. All the three viruses share multiple basic amino acids (R-E-R-R-R-K-K-R) at the cleavage site between HA1 and HA2 domain, that is associated with highly pathogenic H5 avian viruses. Except one more glycosylation site located at 156 position in the chicken strain, there were 7 glycosylation sites at same positions in three virus HA protein molecules. The analysis of NA protein molecule indicated that the stalk region which extends from the viral membrane up to amino acid 85, human and chicken viruses had a 19 amino-acid deletion as compared with that of goose virus, while the goose NA gene was closely related to A/Parrot/Ulster/73 (H7N1) virus. Therefore, goose H5N1 virus HA and NA genes were avian in origin and were different from those of human and chicken H5N1 viruses. In our knowledge, this is the first time that the avian H5N1 virus was found causing influenza outbreak in goose. Why was A/Goose/Guangdong/2/96(H5N1) virus virulent for geese? It might be related to the substitution of amino acid located at 138 position near by RBS on HA protein molecule and 19 amino acids insertion on NA protein molecule as compared with those of human and chicken H5N1 viruses.

Amino Acid Sequence↗
PubMed1997

Reduction of geometric and intensity distortions in echo-planar imaging using a multireference scan.

Echo-planar imaging (EPI) is very sensitive to patient-induced field inhomogeneity caused by susceptibility changes between different anatomical regions. This results in geometric and intensity distortions in the image, especially near tissue/air and tissue/bone interfaces. A new approach is presented to reduce geometric and intensity distortions in EPI. A phase-encoded multireference scan is used to estimate the amplitude and phase errors in the measured signals due to the field inhomogeneity. The EPI data is corrected using both the amplitude and phase of the measured errors. This technique has been evaluated using EPI pulse sequences implemented with conventional gradients and implemented with imaging systems that have special resonating gradients and fast analog to digital converters. The results in both phantom and human studies show that in the absence of object motion the new correction technique can effectively reduce the geometric and intensity distortions.

Cerebellum↗
PubMed1997

Kaposi's sarcoma-associated human herpesvirus-8 encodes homologues of macrophage inflammatory protein-1 and interleukin-6.

Human herpesvirus-8 (HHV-8) has been detected in Kaposi's sarcoma (KS) lesions of all types (AIDS-related, classical and endemic), in body-cavity-based B-cell lymphomas (BCBLs) and in lesions of multicentric Castleman's disease (MCD). We have identified a major gamma-herpesvirus-divergent locus (DL-B) in HHV-8 DNA encoding several HHV-8 unique open reading frames (ORFs), including a homologue of interleukin-6 (IL-6) and two homologues of macrophage inflammatory protein MIP-1. We show that the HHV-8-encoded IL-6 homologue (vIL-6) shares functional properties with endogenous IL-6 proteins and that both vIL-6 and vMIP-1 transcripts are present at high levels following butyrate induction of an HHV-8' BCBL cell line. Low amounts of constitutive vIL-6, but not vMIP-1, mRNA were also detected. The presence of a functional IL-6 homologue encoded by HHV-8 may provide a mechanistic model for the hypothesized role of HHV-8 in KS, MCD and BCBL that involves the mitogenic effects of vIL-6 on surrounding cells. MIP-1 proteins may enhance these effects through the chemotactic recruitment of endogenous cytokine-producing cells into affected tissues and could potentially influence HIV disease progression in coinfected individuals through interactions with the HIV co-receptor CCR-5.

Amino Acid Sequence↗
PubMed1996

Muscarinic activation inhibits T-type Ca2+ current in hen granulosa cells.

The effect of the muscarinic agonist carbachol on Ca2+ currents in hen granulosa cells isolated from the largest ovarian follicle was studied. The major Ca2+ current observed using the perforated patch technique with a recording solution containing 10 mM Ca2+, but no Na+ or K+, exhibited characteristics typical of T-type Ca2+ current: maximal amplitude at -20 mV, rapid inactivation (half-time of 42 +/- 3 msec at -20 mV), inhibition by 100 microM Ni2+, and insensitivity to the dihydropyridine Ca2+ channel antagonist, nifedipine. In all cell studied, carbachol (0.5 mM) caused an inhibition of this current (elicited by depolarizing pulses from -70 to -20 mV) to an average maximal decrease of 90 +/- 2% below basal values. In some 50% of the cells, the Ca2+ current also partially recovered during the 10-min exposure to the muscarinic agonist. These effects were prevented by the muscarinic antagonist atropine (1 microM). To test whether this inhibition was due to increases in intracellular free Ca2+ concentrations ([Ca2+]i), [Ca2+]i was simultaneously measured in fura-2-loaded cells. For cells incubated in normal solution, [Ca2+]i was 0.15 +/- 0.02 microM, but increased to 0.25 +/- 0.6 microM in cells exposed to the recording solution. Under these conditions, carbachol failed to produce the expected [Ca2+]i transients, but, rather, caused a small decrease (8 +/- 2%) in basal [Ca2+]i attributable to its diminution of Ca2+ current. Thus, the results demonstrated an important muscarinic inhibition of the T-type Ca2+ current not related to [Ca2+]i fluctuations. They indicate, on the other hand, that [Ca2+]i can strongly modulate carbachol-induced mobilization of Ca2+ from the intracellular stores.

Animals↗
PubMed1996

[The prospective study on the scope of extended operation for endometrial carcinoma].

OBJECTIVE: To investigate the scope of extended operation for endometrial carcinoma. METHODS: 105 patients underwent extended or less extended hysterectomy plus pelvic and/or para-aortic lymphadenectomy and 36 patients underwent less radical hysterectomy only. Prospective investigation of these 141 cases of endometrial carcinoma was undertaken. RESULTS: Of the 105 cases, lymph node metastasis (18.10%) occurred in 19 cases. Metastasis were found in all stages except stage Ia. The incidences of lymph node metastasis in stage Ib and stage Ic were 8.82% and 21.05% respectively. Of the 141 cases of extended or less extented hysteretomy, 2 were with parametrial connective tissue metastasis (stage II and stage III b), 2 with parametrial lymph node metastasis (stage I c and stage III b) and 2 with parametrial vascular involvement (stage I b and stage I c). CONCLUSIONS: The extended or less extended hysterectomy and lymphadenectomy should be performed in all patients of endometrial carcinoma except those of stage I a.

Adenocarcinoma↗
PubMed1996

[Studies on distribution patterns of modulator CGRP in different motoneuron pools in rats].

Using retrograde labelling combined with calcitonin gene-related peptide (CGRP) immunocytochemistry technique, distribution patterns of the content of calcitonin gene-related peptide-like immunoreactivity (CGRP-LI) were studied in two different motoneuron (Mn) pools supplying soleus (SOL, slow-twitch muscle) and extensor digitorium longus (EDL, fast-twitch muscle) of hindlimbs in rats during development. The Mn pools were identified with a novel retrograde tracer, choleragen B subunit (CB) coupled with colloidal gold (CB-Au, 5 nm particle, prepared by ourselves), which was injected into EDL or SOL. After the silver intensification for visualizing colloidal gold particles, CGRP immunocytochemistry were processed. The CB-Au retrogradely identified Mns in each Mn pool were counted and CGRP-LI intensity of Mns was evaluated as strong, moderate, weak and negative. The double labelling revealed different distribution patterns of CGRP-LI content between SOL and EDL Mn pools during development. Comparing the level of CGRP expression between the two Mn pools, SOL Mn pool had a higher ratio of neurons lacking CGRP-LI/weak CGRP LI and a lower proportion of strongly CGRP-LI labelled ones. These results suggest that the difference in content of CGRP-LI in Mns is related to the type of muscular motor activity.

Animals↗