Biomedical subjects

C Hang

Publications and source records attributed to C Hang.

14 recordsLinked to original sources

PubMed2001

[Sequencing and comparative analysis of the complete glycoprotein gene of three Crimean-Congo hemorrhagic fever virus Chinese isolates].

OBJECTIVE: To determine the complete sequences of glycoprotein (M) gene of Crimean-Congo hemorrhagic fever virus (CCHFV) Chinese isolates (Xinjiang hemorrhagic fever virus, XHFV) BA66019, BA8402 BA88166 and to compare and analyze the relationships among the viruses. METHODS: Based on the conserved reverse complementarity of the CCHFV genomic termini, a primer PCM-Tag was designed and used together with random hexmers to initiate reverse transcription of viral RNA to synthesize cDNA. The latter was amplified with single primer PCM-Tag using the proof-reading DNA polymerase to produce the complete M gene. The PCR products were gel-purified and the whole M segment was sequenced and the comparison and analysis were performed aided by computer for the phylogenesis and coding strategy. RESULTS: Comparison of the whole M gene sequences of XHFV reference strain BA66019 with international prototype CCHFV IbAr10200 showed an excess of 5 base pairs in length, resulting in 5,365 bp; while BA8402 and BA8816 are 5,365 bp long, 4 more base pairs than IbAr10200. The first start codons of long ORFs were located at the 78th base pair in M gene of BA66019, BA8402 and BA88166, which were 15 base pairs prior to that of IbAr10200. The precursors encoded by these M genes were totaled 1,689 amino acids (AA), 6 AAs more than that of IbAr10200. The similaries between CCHFV M genes in nucleotide level were: 80.9% (IbAr10200-BA66019), 80.2% (IbAr10200-BA8402), 80.2% (IbAr10200-BA88166), 83.7% (BA8402-BA66019), 83.6% (BA88166-BA66019), and 99.0% (BA8402-BA88166), respectively. The corresponding similarities in amino acid level were 85.1%, 86.3%, 86.6%, 87.8%, 88.0%, and 98.8%, respectively. The similarities of M genes of CCHFVs and Dugbe virus in both nucleotide and amino acid levels were around 55% and 37%, which were much lower than those among CCHFVs. CONCLUSION: The M genes of XHFVs and IbAr10200 formed respective independent phylogenetic branches genetically and the human-origin isolate BA88166 might be a variant of tick-borne BA8402, suggesting that there was only one kind virus prevailing in Xinjiang epidemic areas in 1980s.

Amino Acid Sequence↗

PubMed2001

Soluble Tie2 and Flt1 extracellular domains in serum of patients with renal cancer and response to antiangiogenic therapy.

Antiangiogenesis drugs can be difficult to evaluate because they produce disease stabilization rather than tumor regression. Markers of endothelial mass in tumors may be of value to monitor therapy and evaluate such drugs. Soluble domains of the endothelial receptor tyrosine kinases, sTie2 (angiopoietin receptor) and sFlt1 (vascular endothelial growth factor receptor-1) were analyzed by sandwich ELISA in serum samples from 43 patients with advanced renal cancer before and 1 month after antiangiogenic therapy with razoxane. Pretreatment sFlt1 levels were 0.77 ng/ml +/- 0.48 (SD) and sTie2 74.3 ng/ml +/- 15 (SD). Pretreatment sFlt1 levels above the median were associated with a lesser chance of stable disease (P = 0.04) and poorer survival (P = 0.01). Fall of sTie2 on treatment was associated with stable disease (P = 0.05) and improved survival (P = 0.04). The soluble receptors measured weeks before response were assessed and correlated with response and survival, showing they may be useful to monitor and develop antiangiogenic therapy.

Antineoplastic Agents↗

PubMed2000

Genetic diversity of hantaviruses isolated in china and characterization of novel hantaviruses isolated from Niviventer confucianus and Rattus rattus.

The antigenic and genetic properties of 46 hantaviruses from China, 13 from patients, 23 from rodents, and 10 from unknown hosts, were compared with those of other hantaviruses. The viruses were classified as either Hantaan (HTN) or Seoul (SEO) viruses. A phylogenetic analysis of the partial M (300 bp) and S (around 485 bp) genomes of HTN viruses identified nine distinct genetic subtypes, one consisting of isolates from Korea. The SEO viruses were divided into five genetic subtypes, although they had less variability than the HTN subtypes. There was a correlation between the subtype and province of origin for four subtypes of HTN viruses, confirming geographical clustering. Hantaan virus NC167 isolated from Niviventer confucianus and SEO virus Gou3 isolated from Rattus rattus were the basal clades in each virus. The phylogenetic trees constructed from the entire S and M segments suggested that NC167 was introduced to N. confucianus in a host-switching event. The reactivity of a panel of 35 monoclonal antibodies was almost exactly the same in NC167 and a representative HTN virus and in Gou3 and a representative SEO virus. However, there was a one-way cross-neutralization between them. These results confirm the varied nature of Murinae-associated hantaviruses in China.

Animals↗

PubMed2000

Isotope effects and the mechanism of allylic hydroxylation of alkenes with selenium dioxide.

The mechanism of the allylic oxidation of 2-methyl-2-butene with selenium dioxide was explored by a combination of experimental and theoretical studies. A comparison of the experimental (13)C and (2)H kinetic isotope effects with predicted values shows that the observed isotope effects are consistent with an initial concerted ene step mediated by SeO(2). However, this comparison also does not rule out the involvement of a selenous ester in the ene reaction or a stepwise reaction involving reversible electrophilic addition of HSeO(2)(+) followed by rate-limiting proton abstraction. Becke3LYP calculations strongly favor SeO(2) over a selenous ester as the active oxidant, with the predicted barrier for reaction of 2-methyl-2-butene with SeO(2) being 21-24 kcal/mol lower than that for reaction with H(2)SeO(3). The possibility of a selenous ester being the active oxidant is also disfavored by the observation of oxidations in non-hydroxylic solvents. The involvement of HSeO(2)(+) does not appear consistent with a lack of dependence of the reaction on the basicity of the reaction mixture. A concerted ene reaction with SeO(2) as the active oxidant appears to be the major mechanistic pathway operative in these reactions.

Alkenes↗

PubMed2000

Voltage-sensor sodium channel mutations cause hypokalemic periodic paralysis type 2 by enhanced inactivation and reduced current.

The pathomechanism of familial hypokalemic periodic paralysis (HypoPP) is a mystery, despite knowledge of the underlying dominant point mutations in the dihydropyridine receptor (DHPR) voltage sensor. In five HypoPP families without DHPR gene defects, we identified two mutations, Arg-672-->His and -->Gly, in the voltage sensor of domain 2 of a different protein: the skeletal muscle sodium channel alpha subunit, known to be responsible for hereditary muscle diseases associated with myotonia. Excised skeletal muscle fibers from a patient heterozygous for Arg-672-->Gly displayed depolarization and weakness in low-potassium extracellular solution. Slowing and smaller size of action potentials were suggestive of excitability of the wild-type channel population only. Heterologous expression of the two sodium channel mutations revealed a 10-mV left shift of the steady-state fast inactivation curve enhancing inactivation and a sodium current density that was reduced even at potentials at which inactivation was removed. Decreased current and small action potentials suggested a low channel protein density. The alterations are decisive for the pathogenesis of episodic muscle weakness by reducing the number of excitable sodium channels particularly at sustained membrane depolarization. The results prove that SCN4A, the gene encoding the sodium channel alpha subunit of skeletal muscle is responsible for HypoPP-2 which does not differ clinically from DHPR-HypoPP. HypoPP-2 represents a disease caused by enhanced channel inactivation and current reduction showing no myotonia.

Action Potentials↗

PubMed2000

13C and (2)H kinetic isotope effects and the mechanism of Lewis acid-catalyzed ene reactions of formaldehyde.

13C and (2)H kinetic isotope effects were determined for the ene reaction of formaldehyde with 2-methyl-2-butene at natural abundance catalyzed by diethylaluminum chloride. The reactive methyl group exhibits a k(12)(C)/k(13)(C) of 1.006-1.009 and a k(H)/k(D) of approximately 1.22-1.23. The latter represents a combination of primary and secondary effects and is consistent with a significant primary deuterium isotope effect. A very close correspondence of the other isotope effects with the equilibrium isotope effects predicted for formation of a model intermediate cation is observed. An intermolecular deuterium isotope effect of 2.0-2.5 was observed under several reaction conditions in the Lewis acid-catalyzed reaction of formaldehyde with d(0)/d(12)-tetramethylethylene. The results are interpreted as supporting the reversible formation of an essentially classical open cation followed by rate-limiting proton transfer.

Acids↗

PubMed2000

[Isolation, identification and certain characteristics of a Hantaan virus proposed as candidate virus for killed vaccine].

OBJECTIVE: Isolation and identification of a Hantaan virus from HFRS patient's serum for killed vaccine development. METHODS: This virus temporally called FT14 detected by IFAT, RT-PCR. Partial sequence of M segment was determined by Sanger' a dideoxy chain termination method. RESULTS: The antigenicity and PCR amplification of the newly isolated virus FT14 proved that it belongs to virus of HTN type. Antiserum to the virus can neutralize many strains of Hantaan virus from different areas. The partial sequence of M segment of FT14, as compared with other HTN strains, showed great differences among nucleotide sequences, while the deduced amino acid sequence is comparatively conservative. The titer of the virus reached its peak at 9 days post inoculation in vitro, then the peak titer could last for a long time. CONCLUSIONS: This virus strain FT14 would be a good candidate virus for killed vaccine development.

Amino Acid Sequence↗

PubMed1999

Cavernous hemangiomas in the cavernous sinus. Case reports.

BACKGROUND: Extra-axial cavernous hemangiomas are rare and have a propensity to develop within the cavernous sinus. Total removal of these vascular tumors is difficult due to the risk of severe intraoperative bleeding and the complicated neurovascular structures of the cavernous sinus. Only a small number of cases have been reported to be successfully totally removed. METHODS: Retrospective studies were done in three cases of extraaxial cavernous hemangiomas located in the cavernous sinus. All three patients presented with clinical symptoms common to other tumors located in the region, such as headache and impairment of cranial nerve function. Their preoperative MRI results showed significant hyperintensity on T2-weighted images and marked enhancement with gadolinium-DTPA that delineated a sharp tumor margin. RESULTS: All three patients underwent total tumor removal, with an uneventful postoperative course. There was no postoperative neurological deficit in one patient, and a complete ophthalmoplegia and diminished sensation in the V1 distribution in two patients. Three months after operation, follow-up MRI or CT scan showed no residual tumor. CONCLUSION: Surgical resection of these lesions was possible but difficult because of severe bleeding. Avoiding piecemeal removal before the main feeding arteries are interrupted can minimize intraoperative bleeding.

Adult↗

PubMed1999

Three-dimensional changes in the upper airway during neuromuscular stimulation of laryngeal muscles.

During swallowing, airway protection depends upon adequate glottal closure and laryngeal elevation to prevent the entry of substances into the airway. Three-dimensional changes in the upper airway during laryngeal muscle stimulation in a canine model were quantified in animals implanted with Peterson type stimulating electrodes in the inferior and superior portions of the thyroarytenoid muscle, together with a reference electrode. Computer tomography scanning was performed on an IMATRON scanner with a 3 mm slice thickness advanced at overlapping 1 mm increments. Stimulation of the thyroarytenoid muscle produced adductions of the vocal fold towards the midline and changes in the supraglottic region as well as the glottis; the glottic wall was compressed medially above and below the glottis. These results suggest that chronic neuromuscular stimulation can effect glottic protection by reducing the glottal opening and may be beneficial for patients with central control disorders affecting airway protection during swallowing.

Animals↗

PubMed1999

Cavernous hemangiomas in the cavernous sinus.

OBJECTIVE: Cavernous hemangiomas located within the cavernous sinus are rare vascular tumors that are very difficult to remove because of severe intraoperative bleeding. The purpose of this study was to analyze the clinical, neuroimaging, and pathological features and the surgical treatment of these tumors. METHODS: Ten patients with cavernous hemangiomas in the cavernous sinus who were surgically treated from August 1985 to October 1997, in our hospital, were retrospectively studied. RESULTS: Among the 10 patients, total tumor removal was performed in four cases, partial removal in two cases, and tumor biopsies in four cases. The four patients who underwent total tumor removal experienced uneventful postoperative courses, with no postoperative neurological deficits for one patient, no new neurological deficits for two patients, and complete ophthalmoplegia and diminished sensation in the distribution of Cranial Nerve V1 for one patient. The two patients who underwent partial removal developed complete ophthalmoplegia and diminished sensation in the distribution of Cranial Nerve V1 after surgery, and one of them experienced contralateral paralysis. All four patients who underwent tumor biopsies experienced severe intraoperative tumor bleeding; one exhibited Cranial Nerve III, IV, and VI injuries after surgery. CONCLUSION: The features of prominent hyperintensity in T2-weighted scans, with well-defined borders in enhancing magnetic resonance imaging scans, or marked enhancement in computed tomographic and magnetic resonance imaging scans, with no tumor blush in angiographic analyses, facilitate the diagnosis of these tumors. These tumors can be divided into two subgroups on the basis of intraoperative findings and pathological features. We do not recommend division and piecemeal removal of the tumor during surgery if the main supplies of the tumor have not been interrupted.

Adult↗

PubMed1999

[The treatment of 432 patients with pituitary adenomas via transsphenoidal approach].

OBJECTIVE: To study some clinical features of 432 cases of pituitary adenomas treated by transsphenoidal microsurgery between July 1982 and October 1996. METHODS: Pathological examination, immunohistochemical examination and electronmicroscopic examination were done in 424, 29 and 103 cases respectively. RESULTS: Hyperprolactinemia was found in many so-called non-functioning adenomas besides in prolactinomas. The dura maters were invaded by tumors in 78 cases (the incidence of dural invasion was 65.5%). CONCLUSIONS: Hyperprolactinemia is not peculiar to prolactinomas, and differential diagnosis is necessary when hyperprolactinemia exists. The involvement of the dura mater of sellar floor is an important mark that the adjacent tissues were invaded by pituitary adenomas. The outcome of surgical treatment is significantly different between the patients with dural invasion and without invasion.

Adenoma↗

PubMed1998

Nucleotide sequence and phylogenetic analysis of the medium (M) genomic RNA segments of three hantaviruses isolated in China.

The medium (M) genome segment of hantaviruses (family Bunyaviridae) encodes the two virion glycoproteins. G1 and G2, as a precursor protein in the complementary sense RNA. We determined the nucleotide sequences of the M genome segments of three Chinese hantavirus isolates, a Hantaan-type (HTN) virus designated A9 and two Seoul-type (SEO) viruses designated L99 and HB55, and compared them to those of other HTN or SEO viruses isolated in Eastern Asia. The M segment of A9 is 3616 nucleotides in length and shows 99.5% identity at the nucleotide level and 99.1% identity at the amino acid level to that of the Chinese HTN isolate HV114. The M segments of L99 and HB55 are 3652 nucleotides in length, one nucleotide longer than the M segments of other sequenced SEO isolates such as SEO 80-39, SR-11, and Biken-1. The Chinese SEO isolates showed 95% nucleotide sequence identity and 99% amino acid sequence identity to SEO 80-39. We also sequenced a 736 nucleotides region of the M genome segment of another Chinese SEO isolate, R22, which revealed errors in the published data. Phylogenetic analysis of the available sequences indicated that both the Chinese HTN- and SEO-type viruses form lineages distinct from those of the isolates from other parts of Eastern Asia.

Amino Acid Sequence↗

PubMed1994

Antigenic and molecular characterization of hantavirus isolates from China.

Hemorrhagic fever with renal syndrome (HFRS) is caused by certain viruses in the genus Hantavirus, family Bunyaviridae, and is a major public health problem in China. By using molecular and serological tests, we characterized 15 hantaviruses isolated either from patients with HFRS or from rodents captured in endemic areas of China. By cross plaque-reduction neutralization tests performed with rabbit immune sera, we identified two serologically distinct groups of viruses, comprised of those related to Hantaan virus, and those related to Seoul virus. To study the genetic relationships among these viruses, we amplified a 330 base pair region of the medium (M) genome segment of each isolate by reverse transcription and polymerase chain reaction (PCR) and compared the nucleotide sequences to those of other, well-characterized hantaviruses. In addition, we PCR-amplified and analyzed the entire coding region of the small (S) genome segment of each isolate by restriction enzyme digestion with a battery of enzymes. The results of our genetic analyses of both the M and S segments of these isolates confirmed our serological data, indicating that Hantaan and Seoul viruses co-circulate in endemic disease regions of China. We constructed a phylogenetic tree based on multiple alignment of the partial M segment sequences. The resulting dendrogram distinguished three genetic subtypes of Hantaan viruses and one type of Seoul virus.

Animals↗

PubMed1992

[Functional evaluation of possible cytokine receptors on airway smooth muscle: modification of airway smooth muscle responses by cytokines].

Recently, the role of activated T-cell derived cytokines in the pathophysiology of asthma has been recognized. In this study, we evaluated the effects of interleukin-2 (IL-2) and gamma interferon (IFN-gamma) on contractile and relaxing responses of guinea-pig tracheal strips in isometric tension measurement system. IL-2 enhanced carbachol (Carb)- and KCl-induced contraction, and attenuated isoproterenol (Iso)-induced relaxation. IFN-gamma had little effect on Carb and KCl contraction, but enhanced Iso relaxation. These effects of cytokines were abolished by denuding epithelium from tracheal strips. These results suggest that IL-2 and IFN-gamma are able to affect functions of non-immune cells in the airway, and that the airway epithelium has some role in the effects of cytokines on airway responses.

Animals↗