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Biomedical subjects

W Wen

Publications and source records attributed to W Wen.

At least 55 records · Page 3Linked to original sources
PubMed1998

UGA codon position affects the efficiency of selenocysteine incorporation into glutathione peroxidase-1.

A UGA codon and a selenocysteine insertion sequence in the 3'-untranslated region are the only established mRNA elements necessary for selenocysteine (Sec or U) incorporation during translation. These two elements, however, do not universally confer efficient Sec incorporation. The objective of this study was to systematically examine the effect of UGA codon position on efficiency of Sec insertion. In a glutathione peroxidase-1 (F-GPX1) expression vector, the UGA at the native position (U47) was mutated to a cysteine codon, and codons for Ser-7, Ser-12, Ser-18, Ser-29, Ser-45, Ser-93, Cys-154, Val-172, Ser-178, and Ser-195 were individually mutated to UGA and transiently expressed in COS-7 cells. 75Se incorporation at the 11 positions was 31, 72, 54, 105, 90, 100, 146, 135, 13, 11, and 43%, respectively, of 75Se incorporation at U47, suggesting that Sec is more efficiently incorporated at UGA codons positioned in the middle of the coding region rather than close to the 5' or 3' ends. Ribonuclease protection showed that these differences were not due to differences in mRNA level. When the green fluorescence protein (GFP) coding region was placed in-frame at the 5' or 3' ends of the coding region in F-GPX1 to produce chimeric 50-51-kDa GFP/GPX1 proteins, Sec incorporation at UGA codons, formerly close to the 5' or 3' ends, was increased to levels comparable to the UGA at U47. Insertion of GFP after the UAA-stop was just as effective in increasing Sec insertion efficiency as GFP inserted before the stop. These studies used a recombinant expression model that incorporated Sec at non-native UGA codons at rates equal to those of endogenous glutathione peroxidase-1 and showed that the efficiency of Sec incorporation can be modulated by UGA position; Sec incorporation at high efficiency appears to require that the UGA be >21 nucleotides from the AUG-start and >204 nucleotides from the selenocysteine insertion sequence element.

3' Untranslated Regions↗
PubMed1998

Endogenous protein kinase A inhibitor (PKIalpha) modulates synaptic activity.

Protein kinase A (PKA) has long been known to be involved in major regulatory mechanisms underlying synaptic plasticity and complex behaviors such as learning and memory. The endogenous PKA inhibitor, PKIalpha, has been extensively studied for its effects on PKA and PKA-mediated signal transduction. Clear functions for PKIalpha in vivo, however, remain to be established. Here we describe that several forms of synaptic stimulation in the rat hippocampus cause a dramatic decrease in the concentration of PKIalpha in dentate granule cells. Furthermore, chronic infusion of antisense oligonucleotides against PKIalpha into the rat brain results in a dramatic reduction of the excitability of these neurons and elimination of their ability to exhibit long-term potentiation (LTP) and long-term depression (LTD), suggesting a stimulus-dependent regulatory role for PKIalpha in PKA signal transduction.

Adaptor Proteins, Signal Transducing↗
PubMed1998

Congenital abnormalities in children with acute leukemia: a report from the Children's Cancer Group.

OBJECTIVE: To evaluate the risk of leukemia associated with congenital abnormalities, a series of matched case-control studies were carried out by the Children's Cancer Group. STUDY DESIGN: Eligible case patients for this analysis included individuals with a diagnosis of leukemia confirmed at a Children's Cancer Group member institution: 2117 diagnosed with acute lymphoblastic leukemia (ALL) and 605 diagnosed with acute myelogenous leukemia (AML). Case patients were compared with matched regional population control subjects selected by using a modified random digit dialing method. Data regarding congenital abnormalities in index children and their siblings were collected by telephone interview with the biologic mother. Relative risk was estimated by using the odds ratio (OR). RESULTS: More congenital abnormalities were reported in index case patients with ALL than in control subjects, with statistically significant increases in multiple birthmarks (OR = 1.35), Down syndrome (OR = 4.85), congenital heart defects (OR = 1.48), and pancreas-digestive tract abnormalities (OR = 2.52). Similarly, birth defects were reported more often among index case patients with AML than control subjects (OR = 2.90), with significant increases in multiple birthmarks (OR = 1.89), Down syndrome (OR = 76.80), mental retardation (OR = 14.47), and congenital heart defects (OR = 2.07). Exclusion of case patients with Down syndrome from the analysis did not change the statistically significant excess of pancreas-digestive tract abnormalities in case patients with ALL or the excess of multiple birthmarks observed in both case patients with ALL and those with AML. For both the ALL and AML analyses, no significant differences in the number of reported congenital abnormalities were seen between siblings of case patients and siblings of control subjects. CONCLUSION: Many of the observed associations with congenital abnormalities occurred in the children with Down syndrome, who are known to have an increased risk for leukemia. The higher reported frequency of birthmarks among case patients may suggest a genetic component to leukemia risk.

Adolescent↗
PubMed1998

[Experimental study on delayed reinnervation of laryngeal adductor and abductor].

To investigate time of delayed reinnervated laryngeal muscle, 15 dogs were divided into two groups. The right recurrent laryngeal nerves of 10 dogs in experimental group were cut, and repaired at 4, 6, 8, 10 and 12 months intervals by transposition of the phrenic nerve to the recurrent laryngeal nerve after cutting and suturing the adductor branch to the main branch of ansa cervicalis. The right recurrent laryngeal nerves of 5 dogs in control group were cut, but did not repair. Laryngoscope, electromyography, contractile tension of laryngeal muscle and histologic studies were performed at six months postoperatively. The results showed that fair recovery of adduction and abduction was noted within ten months interval, and the effect of adduction was better than that of abduction. The effect decreased gradually with the denervated time increased. The conclusion demonstrated that delayed reinnervation of laryngeal muscle should be performed within ten months.

Animals↗
PubMed1998

[Change of cricoarytenoid joint after recurrent laryngeal nerve damaged].

The arytenoid mobilities and histological changes of cricoarytenoid (CA) joints were observed in 1, 2, 4, 6, 8, 10, 12 months after the injury of recurrent laryngeal nerve (RLN). Eighteen adult dogs were randomly divided into three groups: 1. Unilateral RLN partial damaged (4/18), 2. Unilateral RLN complete damaged (7/18), 3. Bilateral RLN damaged (7/18). The results demonstrated that arytenoid mobilities return to normal and no fibroses of CA joints were found in 6 months after RLN injury in group one. The arytenoid fixations were found in 6 and 4 months after RLN injury in group two and three, respectively. The fibroses of CA joints were more severe in group three than group two after RLN injury.

Animals↗
PubMed1998

[Study on contractile properties of the posterior cricoarytenoid muscle after delayed reinnervation].

To study date on the contractile properties of posterior cricoarytenoid muscle after delayed reinnervation of different reinnervated methods. Twenty four dogs were reinnervated at 0,4,5,6,10 and 12 month interval following recurrent laryngeal nerve via the phrenic nerve anastomosed to the recurrent laryngeal nerve after cutting the adductor branch and ansa cervicalis-sternothyroid muscle pedicle implanted into the posterior cricoarytenoid muscle. After 6 months, a series of contractions were recorded from each side in twenty living dogs. The results showed that contractile force of reinnervated muscle decreased gradually with the time of denervation, but contractile force of muscle was no significantly difference between reinnervated side of nerve anastomosed group in 4 months after denervated and normal side, and it was significantly difference between nerve anastomosed group and nerve-muscle pedicle implanted group at some time of delayed reinnervation. The contractile time of reinnervated side of two operated groups was similar to that of normal side. The conclusion demonstrated that the contractile properties can indicate exactly reinnervated degree of muscle, and the earlier reinnervation was performed, the better curative effect was.

Anastomosis, Surgical↗
PubMed1998

[Change of cell proliferation after the denervation laryngeal adducent muscles in dogs].

OBJECTIVE: To investigate the changes of cell proliferation state after denervation of laryngeal adducent muscles in dog. METHODS: The muscles were obtained from 8 dogs with recurrent lanyrgeal nerves injured. The cross sectional areas of muscle cells were measured by VIDS Image Analysis System in HE stained sections. A quantitative collagen/muscle ratio was measured by TJTY-300 image analysis system in Van Gieson stained sections. The percentages of S phase cell nucleus were calculated by image cytometry/DNA quantitative analysis with CAS 200 System. RESULTS: It showed that the cross sectional area of muscle cells decreased gradually after denervation (out-standing in 6 months after denervation) and collagen/muscle ratio increased significantly with time. The percentage of S phase nucleus was high at 5 months and then decreased. CONCLUSION: The proliferation of thyroarytenoid muscle and lateral cricoarytenoid muscle cell of dog remained at high level in 5 months after denervation and then slowed down and atrophy of muscles occurred 6 months after denervation. This suggests that nerve repair should be performed early. Examination of cell proliferation might indicate if the denervation of cells irreversible. It is helpful in choosing proper surgery and estimating the effect of nerve repair.

Animals↗
PubMed1998

[Treatment of the unilateral paralysis of vocal fold--comparison between laryngeal framework surgery and reinnervation].

OBJECTIVE: To compare the effects of laryngeal framework surgery and reinnervation in the treatment of unilateral paralysis vocal fold. METHODS: Twenty-three cases of unilateral vocal fold paralysis were operated with laryngeal framework surgery and reinnervation and the voice assessment, acoustic analysis, laryngoscopy, electromyography were done pre- and postoperatively. RESULTS: The short and long term curative effects of the laryngeal framework were good, but with regard to long term result, the reinnervation that can recover the thickness, elasticity and tension of vocal fold was better, and the earlier was the operation done, the better would be the result. CONCLUSION: These two operations were both effective in the treatment of unilateral paralysis of vocal fold, but it should be selected according to the requirement of patient, the pattern of damage, the degree of paralysis and movement of cricoarythenoid joint.

Adult↗
PubMed1997

[Survey of smoking and human health in Guangdong province].

As part of the national plan in China, 28,979 residents or farmers were surveyed in 1991 in Guangdong province to investigate the relation between smoking and human health. The results showed that the total smoking rate was 40.2%, 58.8% was for male and 1.2% was for female. 56.4% was in city and 38.7% was in rural area. The beginning smoking age was 15-16 years old (5.5%). 8.5% smokers started smoking after 25 years old. Smoking can increase risk of diseases. The incidence of chronic bronchitis, hypertension, gastric ulcer and pulmonary TB in smoking group were significantly higher than that in non-smoking group. No difference was found in the symptoms of panting, cough and phlegm between the two groups. To control smoking is one of the important measures for human health.

Adolescent↗
PubMed1997

[Determination of liensinine in plasma by high performance liquid chromatography].

A sensitive method of high performance liquid chromatography (HPLC) for determination of liensinine in plasma is reported. An Ultrasphere Si column, 250 mm x 4.6 mm i.d. with dichloromethaneisopropyl alcohol-diethylamine (75:25:0.2, V/V) as mobile phase at a flow-rate of 1.0 mL/min and UV-detector at 282 nm were used. Neferine was served as the internal standard. Liensinine in plasma was extracted with diethyl ether three times after adding ammonia-ammonium chloride buffer (pH 10). Liensinine was completely separated from nefrine. The retention times of liensinine and neferine were 8.5 and 5.0 minutes, respectively. The calibration line of liensinine was linear in the range of 0.0625-5.0 mg/L (r = 0.9996). The mean recovery was 93.6% with RSD of 1.9%. The precision of intra-day and inter-day for liensinine was in the range of 1.4%-4.1% and the detectable limit was 0.025 mg/L based on a signal-to-noise ratio of 3. The results showed that the method was simple and sensitive.

Chromatography, High Pressure Liquid↗
PubMed1996

Experimental study on reinnervation of vocal cord adductors with the ansa cervicalis.

The purpose of this study was to reestablish the adduction of the paralyzed vocal cord through reinnervation of the adductor muscles for unilateral vocal cord paralysis. In nine dogs, the adductor branch of the recurrent laryngeal nerve was anastomosed to the main branch of the ansa cervicalis. Six months later, various techniques of observation showed that seven of nine cases had excellent to good adduction during whining. Adduction was caused by reinnervation of the adductor muscles from the ansa cervicalis as demonstrated by laryngeal spontaneous and evoked electromyography, contraction tension, and various histologic findings. Therefore, the new technique could be a good treatment of unilateral vocal cord paralysis.

Animals↗
PubMed1996

Update: laryngeal reinnervation for unilateral vocal cord paralysis with the ansa cervicalis.

Eight patients underwent ansa cervicalis anastomosis to the adductor branch of the recurrent laryngeal nerve for unilateral vocal cord paralysis. They were followed long enough (at least 1 year) to determine if the procedure was successful. All cases have been subjected to preoperative and postoperative voice recording, acoustic analysis, and videolaryngoscopy. Some of them have been subjected to stroboscopy and electromyography (EMG). Data from these cases indicate that satisfactory phonatory quality may be achieved after the procedure. The reinnervated vocal cord neither abducted nor adducted, but it presented itself in midline for precise apposition with the normal cord. Synchronous mucosal waves in both vocal cords could be observed. EMG showed that the procedure produced satisfactory reinnervation of the adductory muscles. Therefore, the authors believe that the procedure could be proposed as an alternative to Teflon injection or thyroplasty in selected cases.

Adult↗
PubMed1996

Ras inhibits thyroglobulin expression but not cyclic adenosine monophosphate-mediated signaling in Wistar rat thyrocytes.

We previously reported that microinjection of purified Ras protein stimulated DNA synthesis in quiescent Wistar rat thyrocytes and that TSH (TSH)-stimulated DNA synthesis was Ras-dependent. In contrast to these results, microinjection of cellular or oncogenic Ras significantly reduced TSH-stimulated thyroglobulin (Tg) expression, a marker of thyrocyte differentiation. Microinjection of a dominant inhibitory Ras mutant had no effect on TSH-stimulated Tg expression. As the Tg promoter is cAMP-responsive and Ras was previously reported to interfere with entry of catalytic (C) subunit of the cAMP-dependent protein kinase into the nucleus, experiments were performed to assess the effects of Ras on cAMP-mediated signaling. Microinjection of either cellular or oncogenic Ras had no effect on TSH-stimulated entry of C subunit into the nucleus. Consistent with these data, Ras did not reduce TSH-stimulated cAMP response element binding protein phosphorylation, or cAMP response element-regulated gene expression. These results demonstrate that Ras exerts differential effects on TSH signaling; Ras increases TSH-stimulated DNA synthesis and decreases TSH-induced Tg expression. Moreover, the mechanism through which Ras induces Tg expression lies distal to entry of C subunit into the nucleus, cAMP response element binding protein phosphorylation, and cAMP response element-regulated gene expression.

Animals↗
PubMed1995

Identification of a signal for rapid export of proteins from the nucleus.

Active nuclear import of protein is controlled by nuclear localization signals (NLSs), but nuclear export is not understood well. Nuclear trafficking of the catalytic (C) subunit of cAMP-dependent protein kinase (cAPK) is critical for regulation of gene expression. The heat-stable inhibitor (PKl) of cAPK contains a nuclear export signal (NES) that triggers rapid, active net extrusion of the C-PKl complex from the nucleus. This NES (residues 35-49), fused or conjugated to heterologous proteins, was sufficient for rapid nuclear export. Hydrophobic residues were critical. The NES is a slightly weaker signal than the SV40 NLS. A sequence containing only residues 37-46, LALKLAGLDI, is also sufficient for nuclear export. This is an example of a protein-based NES having no obvious association with RNA. A similar sequence, LQLPPLERLTL, from Rev, an RNA-binding protein of HIV-1, also is an NES.

Amino Acid Sequence↗
PubMed1995

The expression and intracellular distribution of the heat-stable protein kinase inhibitor is cell cycle regulated.

The heat-stable protein kinase inhibitor (PKI) is a potent and specific inhibitor of the catalytic (C) subunit of the cAMP-dependent protein kinase. We report the isolation of a polyclonal antibody raised to purified recombinant PKI alpha. Using this antibody, the intracellular distribution of endogenous PKI alpha was assessed by immunostaining. The PKI alpha expression and intracellular distribution varied as a function of cell cycle progression. PKI alpha expression appeared low in serum-starved cells and in cells in G1 and increased as cells progressed through S phase. Its distribution became increasingly nuclear as cells entered G2/M. Nuclear levels of PKI alpha remained high through cell division and decreased again as cells reentered G1. The cell cycle regulated expression and nuclear distribution suggests a specific role for PKI alpha in the nucleus during the G2/M phases of the cell cycle. Consistent with this, microinjection of PKI alpha antibody into serum-starved cells prevented their subsequent cell cycle progression. Similarly, overexpression of C subunit in cells arrested at the G1/S boundary prevented their subsequent division. Together these results support the idea that PKI alpha plays an important role in the inhibition of nuclear C subunit activity required for cell cycle progression, although a determination of the relative amounts of endogenous nuclear PKI and C-subunit will be required to substantiate this hypothesis.

Animals↗