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Biomedical subjects

M Wu

Publications and source records attributed to M Wu.

At least 19 recordsLinked to original sources
PubMed1992

Segregation analysis of esophageal cancer in 221 high-risk Chinese families.

BACKGROUND: Until recently, environmental factors were considered of greatest importance in the etiology of esophageal cancer. Recent studies, however, have suggested that genetic factors also have a role. PURPOSE: Since no formal genetic study of this cancer has been previously reported, we carried out a statistical analysis to determine how important genetic factors are in the etiology of esophageal cancer in high-incidence areas of North China. METHODS: Using a logistic regressive model, we performed a segregation analysis on 221 high-risk nuclear families from the Yaocun Commune, Linxian, Henan Province of China, with at least one affected family member and with all offspring aged 40 years or older. Three models, the mendelian, the environmental, and the no-transmission models, were each compared with the general-transmission model that incorporated both genetic and environmental factors. RESULTS: According to Akaike's Information Criterion, the mendelian model provided the best fit for the data. By the chi-square test, the mendelian inheritance model was not rejected, but the environmental and the no-transmission models were both rejected. CONCLUSION: The segregation analysis indicated an autosomal recessive mendelian inheritance, with the alleged mendelian gene present at a frequency of 19%, causing 4% of this population to be predisposed to develop esophageal cancer. Large, unmeasured, residual familial factors, however, were also significant. IMPLICATIONS: Both an autosomal recessive gene and unexplained environmental factors appear to be important in the etiology of esophageal cancer in the subpopulation studied.

China↗
PubMed1992

Auditory response properties and spatial response areas of single neurons in the pontine nuclei of the big brown bat, Eptesicus fuscus.

Using free-field acoustic stimulation conditions, we studied the response properties and spatial sensitivity of 146 pontine neurons of the big brown bat, Eptesicus fuscus. The best frequency (BF) and minimum threshold (MT) of a pontine neuron were first determined with a sound broadcast from a loudspeaker placed ahead of the bat. A BF sound was delivered from the loudspeaker as it moved across the frontal auditory space in order to locate the response center at which the neuron had its lowest MT. Then the basic response properties of the neuron to a sound delivered from the response center were studied. As in inferior collicular and auditory cortical neurons, pontine neurons can be characterized as phasic responders, phasic bursters and tonic responders. They have both monotonic and non-monotonic intensity-rate functions. However, most of them are broadly tuned as are cerebellar neurons. Auditory spatial sensitivity was studied for 144 pontine neurons. In 9 neurons, variation of MT with a BF sound delivered from several azimuthal and elevational angles along the horizontal and vertical planes crossing the neuron's response center was measured. In addition, variation in the number of impulses with several stimulus intensities at 10 dB increments above a neuron's MT delivered from each angle was also studied. The auditory spatial sensitivity of other pontine neurons was studied by measuring the response area of each neuron with stimulus intensities at 3, 5, 10, 15 or 40 dB above its lowest MT. The response areas of pontine neurons expanded asymmetrically with stimulus intensity, but the size of the response area was not correlated with either MT or BF. In half of the pontine neurons studied, the response area expanded greatly and eventually covered almost the entire frontal auditory space. The response areas of the other half of the pontine neurons only expanded to a restricted area of frontal auditory space. Two possible neural mechanisms underlying these two types of response areas are hypothesized. The response centers of all 144 neurons were located within a small area of the frontal auditory space. The locations of response centers of these neurons are not correlated with their BFs. The distribution pattern of these response centers is comparable to that of superior collicular and cerebellar neurons but is different from that of inferior collicular and auditory cortical neurons. The results of our study suggest that auditory information is integrated in the pontine nuclei before being further sent into the cerebellum.

Acoustic Stimulation↗
PubMed1992

Isolation and characterization of nuclear proteins that bind to T cell receptor V beta decamer motif.

TCR V beta promoter contains a highly conserved decamer homologous to cAMP response element (CRE). Recent studies have identified this CRE decamer as the dominant transcription-activating element within the TCR V beta promoter. We have isolated cDNA clones, TCR-ATF1 and TCR-ATF2, encoding DNA-binding proteins that recognize this CRE motif. The nucleotide sequence of TCR-ATF1 has not previously been reported, whereas that of TCR-ATF2 was homologous to CRE-BP1, ATF-2, and mXBP. Both TCR-ATF1 and TCR-ATF2 shared a conserved leucine zipper and DNA binding motif with other CRE-binding proteins. TCR-ATF1 and TCR-ATF2 were expressed in all cell lines examined and in mouse embryos as early as 12.5 days. Despite binding to the same CRE motif, TCR-ATF1 and TCR-ATF2 were different from CREB in the fine nucleotide specificity. TCR-ATF bound methylated CRE and CRE mutant M4 (4C----G) that were not recognized by CREB. Additionally, TCR-ATF1 weakly recognized two other single nucleotide mutants of V beta-CRE that were not bound by TCR-ATF2 and CREB. We have further demonstrated that TCR beta-chain expression was immediately activated by cAMP. Such induction is likely mediated through V beta-CRE sequence, because the inclusion of V beta-CRE in a vector with minimum promoter (pBLCAT2) conferred the cAMP inducibility of CAT activity.

Amino Acid Sequence↗
PubMed1992

Separation and spectral data of the six isomeric ozonides from methyl oleate.

The structures of the products obtained on ozonation of methyl oleate have been re-examined. The assignments for the six isomeric ozonides of methyl oleate have been made by 1H and 13C nuclear magnetic resonance (NMR), which were consistent with the retention times observed in high-performance liquid chromatography; the assignments were confirmed by mass and infrared spectroscopy. Two triplets for the ozonide ring protons of the cis and trans isomers in the normal (MOO1) and the two cross ozonides (MOO1 and MOO3) can be resolved by 400 MHz NMR. For MOO1 and MOO3, where the two ring carbons are equivalent, two peaks for the ring carbons of each cross ozonides are resolved in the 13C NMR spectra, one for the cis and one for the trans isomer. For MOO2, four peaks for the ring carbons are resolved in the 13C NMR spectra, two for the cis and two for the trans isomer.

Chromatography, High Pressure Liquid↗
PubMed1992

The chelating-resin modified electrode and its application in the detection of copper in human samples.

A new kind of carbon paste electrodes modified by chelating resin was prepared for detection of trace amount of copper in human hair. As the ion exchange between chelating resin and cupric ions and the coordination reaction on the modified electrode take place at the same time, this method has high sensitivity and good selectivity. The detection limit is 6 x 10(-9) mol/L. The average percentage of recovered copper is 108 +/- 8.3% and the variant coefficient (CV) 7.7%.

Cation Exchange Resins↗
PubMed1992

Clinical trial on termination of early pregnancy with RU486 in combination with prostaglandin.

Termination of early pregnancy was performed in 1572 healthy women with RU486 (mifepristone, 600mg orally once), followed 36-60 hours later by administration of methyl ester of dl-15-methyl-PGF2 alpha (PG05, 1mg vaginal suppository). Complete abortion was accomplished in 91.2% (1433/1571), incomplete abortion in 4.8% (76/1571), and continued pregnancy in 3.9% (62/1571). The time elapsed between RU486 intake and complete expulsion was 2.4 +/- 1.3 days. Expulsion took place on the third day in 935 women (72%), and on the 4th day in 273 women (21.0%). Uterine bleeding occurred on the second or third day after RU486 intake in 1256 women (88.8%), and lasted 11.7 +/- 6.4 (SD) days, range 2-55 days. One subject had blood transfusion due to excessive bleeding. The main side effects were nausea/vomiting (22.3%), abdominal pain (10.2%), headache/dizziness (4.1%) and diarrhea (2.8%). Fatal side effects have not been reported in this study. About 73% of subjects with complete abortion assessed the treatment as good to excellent. Even in the failed cases, 25-42% of subjects considered the treatment as good. Further studies are needed to determine the optimal dose of the RU486 regimen. It should be emphasized that the treatment must be used under close medical supervision in order to monitor the uterine bleeding.

Abortion, Incomplete↗
PubMed1992

A randomized trial of a self-help smoking cessation intervention in a nonvolunteer female population: testing the limits of the public health model.

Reaching nonvolunteer female smokers with effective smoking cessation programs is a critical public health challenge. Smokers (N = 2,786) among 15,004 female members of a health maintenance organization who completed a routine needs assessment were invited into the "UCLA Preventive Health Behavior Study," consisting of five telephone interviews over 2 years assessing health practices. Participants (N = 1,396) were randomized into experimental or control conditions of an unsolicited, mailed, self-help smoking cessation program. Subjects were not alerted to the link between the program and the health study. Smoking status was assessed at 1, 6, 12, and 18 months. Across all subjects, point prevalence at 18 months was 18.62, and continuous abstinence was 2.71%. No difference was found between treatment and control groups regarding smoking status or readiness to stop smoking--raising questions about the value of mailing cessation materials to nonvolunteers. Quit rates increased over the 18-month follow-up; those still smoking at 18 months reported increased readiness to quit. Predictors at each follow-up point were examined multivariately.

Adolescent↗
PubMed1992

Bioavailability of tobacco-specific N-nitrosamines to the snuff dipper.

Use of supercritical carbon dioxide extraction in the analysis of smokeless tobacco for tobacco-specific N-nitrosamines revealed the presence of higher levels of 4-(methylnitros-amino)-1-(3-pyridyl)-1-butanone (NNK) than had been determined with conventional methods. Whether human saliva may be similarly capable of releasing apparently bound NNK during chewing or snuff dipping was tested by incubating smokeless tobacco with enzymatically active saliva and with heat-treated saliva respectively. Enzymatically active human saliva was found to liberate up to twice the amount of the highly carcinogenic NNK than did heat-treated saliva. This is of major consequence for the cancer risk assessment of snuff dippers and tobacco chewers.

Biological Availability↗
PubMed1992

Familial aggregation of oesophageal cancer in Yangcheng County, Shanxi Province, China.

Oesophageal cancer is the second most common cause of cancer death in China and is particularly prevalent in northern China. Genetic factors have been studied less than environmental factors in the aetiology of this disease. This study was conducted to evaluate familial aggregation of oesophageal cancer. All households in Yangcheng County were interviewed in 1979 to determine family history of oesophageal cancer. In 1989, vital status for all family members from three Yangcheng villages was determined and re-interviews were conducted among families who reported a positive family history of oesophageal cancer in 1979. Risk of oesophageal cancer was evaluated by comparing family and individual rates of oesophageal cancer during the 1979-1989 interval stratified by the number of family members with oesophageal cancer prior to 1979. More families with prior oesophageal cancer history reported new oesophageal cancer deaths during the follow-up period than families without prior history (19% versus 5%). Oesophageal cancer rates increased with increasing positivity of family history, and adjustment for other risk factors did not substantially alter this result. We conclude that these data provide evidence for familial aggregation of oesophageal cancer.

Adult↗
PubMed1992

Postantibiotic effect of amikacin and rifapentine against Mycobacterium avium complex.

Postantibiotic effect (PAE) has received little attention in the therapy of chronic intracellular infections, such as those caused by mycobacteria. Amikacin is active therapeutically against Mycobacterium avium complex, even though serum levels exceed the MIC for only a few hours. To determine the PAE of amikacin and rifapentine for M. avium, bacteria were exposed to concentrations of 1x, 4x, and 10x the MIC of each drug for up to 120 min. Regrowth of M. avium was compared with similarly diluted untreated cultures. No PAE was observed on an inoculum of 10(4) bacteria when rifapentine was used at 5x MIC, although a slight inhibition of growth was obtained at 10x MIC for 2 h. For amikacin, PAE was observed up to 48 h at concentrations of 4x and 8x MIC and exposure times of 30-120 min. A PAE of 22 h was seen with 10(7) cfu of M. avium during incubation for 30 min with amikacin at 4x MIC. These results show that amikacin, unlike rifapentine, has a long PAE against M. avium.

Amikacin↗
PubMed1992

Interleukin-6 antagonizes tumor necrosis factor-mediated mycobacteriostatic and mycobactericidal activities in macrophages.

Interleukin-6 (IL-6) is a cytokine produced by a number of cells, including macrophages, and is directly involved in the inflammatory response. The production of IL-6 can be stimulated by monokines such as IL-1 and tumor necrosis factor (TNF). Mycobacterium avium complex organisms frequently cause disseminated disease in patients with AIDS. M. avium is an intracellular bacterium that that mainly infects macrophages. Treatment of M. avium-infected macrophage monolayers with recombinant IL-6 decreased the ability of TNF to activate cultured macrophages to inhibit growth of or kill intracellular M. avium (68% +/- 14% decrease in intracellular killing compared with that in monolayers not treated with IL-6). To further evaluate whether this effect was dependent on the down regulation of membrane receptors to TNF, we examined 125I-TNF binding to macrophages previously exposed to IL-6: the expression of TNF receptors was decreased by 78% +/- 9%. The effect of IL-6 on TNF receptors was observed after 4 h and was reversible. Infection of macrophages with different M. avium serovars was associated with release of IL-6, and IL-6 production peaked at 48 h after infection in concentrations ranging from 328 +/- 87 ng/10(5) cells to 907 +/- 224 ng/10(5) cells. IL-6 did not have any influence on the rate of growth of the tested strains of M. avium within or outside macrophages. These results suggest that release of IL-6 by M. avium-infected macrophages may influence the host's immune response and the outcome of the disease.

Humans↗
PubMed1992

Genetic polymorphisms of alpha-2-HS-glycoprotein, group-specific component and orosomucoid in the Han population, Chengdu, China.

The Han population in Chengdu, China, was investigated for genetic polymorphisms of alpha-2-HS-glycoprotein (A2HS), group-specific component (GC) and orosomucoid (ORM) using isoelectric focusing followed by immunofixation. The allele frequencies were: A2HS*1 = 0.6958,A2HS*2 = 0.3042, GC*1F = 0.4021, GC*1S = 0.3182, GC*2 = 0.2745, GC*1A = 0.0052, ORM1*F1 = 0.7028, ORM1*S = 0.2762, ORM1*F2 = 0.0210, ORM2*A = 0.9965, ORM2*Var = 0.0035.

Alleles↗
PubMed1992

[Human blood stain identification using DNA amplification technique].

DNA was extracted from human's and 15 different species of mammals' dried blood stains as well as from camel hair roots. DNA amplification was carried out using primers of Alu 9.1 and Alu 9.2. The results have indicated that this method can be used for the identification of human's dried blood stain under general condition.

Base Sequence↗
PubMed1992

Pulse repetition rate and duration affect the responses of bat auditory cortical neurons.

Under free field stimulation conditions, we studied the effect of pulse repetition rate and duration on the responses of auditory cortical neurons of the big brown bat, Eptesicus fuscus. The best frequency (BF) and minimum threshold (MT) of each recorded neuron were first determined with a 4 ms pulse delivered from a specific point of the bat's frontal auditory space at which the neuron had maximal spatial sensitivity. Then a 4 ms pulse was delivered repetitively at different rates with an intensity in 10 dB increments above the neuron's MT and its number of impulses and response latency to each combination of repetition rate and intensity were recorded. From the series of isorepetition rate-intensity functions, we identified the neuron's best intensity (BI) which elicited a maximal number of impulses. By using a 4 ms BF and BI pulse delivered at a wide range of repetition rates, we then determined the neuron's best repetition rate (BRR) to which the neuron discharged maximally. The effect of pulse duration on the neuron's responses was subsequently studied by recording its number of impulses and latency to a BF, BI and BRR pulse delivered at a wide range of durations. A neuron's best duration (BD) to which the neuron discharged maximally was also identified. We found that cortical neurons sequentially isolated with an orthogonally penetrated electrode have comparable BFs, MTs and latencies. In addition, high BF neurons tend to have higher MTs and shorter latencies than low BF neurons. Most intensity-rate functions of cortical neurons were nonmonotonic but they can be affected by pulse repetition rate. Under repetitive single pulse stimulation, all cortical neurons show low pass characteristic to pulse repetition rate such that their number of impulses reduced drastically with increasing pulse repetition rate regardless of pulse intensity. The BRRs of most cortical neurons studied are between 1 and 3 pulses/s and their BDs are between 0.5 and 10 ms. Response latencies of cortical neurons generally shortened to a plateau level with increasing pulse intensity. In contrast, they increased with pulse repetition rate and varied in different manner with pulse duration. Nevertheless, a cortical neuron generally responds with a shortest latency to a pulse delivered at its BF, BI, BRR and BD. Thus in auditory signal processing, a neuron's responses to a wide combination of pulse intensity, duration and repetition rate enhance its versatility in signal detection. Its maximal response to a specific combination of signal duration, repetition rate and intensity provides a neural basis for fine analysis of signal features.

Acoustic Stimulation↗
PubMed1992

Retrovirus mediated transfer of antisense human c-myc gene into human esophageal cancer cells suppressed cell proliferation and malignancy.

A retroviral vector, called pDAM3, containing the neomycin resistant gene and the antisense human c-myc gene fragment (the third exon and 3' flanking sequence) was constructed. pDAM3 was introduced into amphotropic packaging cells PA317 by the calcium phosphate precipitation method. Several G418-resistant PA317 clones were isolated. The virus titer of these cell lines was determined by infectivity of their culture fluid to NIH/3T3 cells. The highest titer obtained was 8 x 10(5) G418-resistant colony forming units/ml. Clonal and pooled G418-resistant PA317 colonies with high titers were expanded and analyzed by Southern blot for the presence of intact viral sequences. All cell lines were found to harbor the internal sequences of the pDAM3 vector without any rearrangement. Recombinant virus DAM3 infected human esophageal cancer cell line EC8712 efficiently. The DAM3-infected EC8712 (called EC-DAM3) was found to contain the full DAM3 sequence (4.8 kb) by Southern blot analysis. Antisense myc RNA expressed in the EC-DAM3 cell was detected by RNA hybridization. Further studies indicated that [3H]-thymidine incorporation in EC-DAM3 cells was reduced by 45% in average compared to that in untreated EC8712 cells. Growth rate of EC-DAM3 cells also decreased about 50%. DAM3-infected EC8712 cells lost their ability of forming tumor in nude mice. It thus appeared that the antisense myc gene introduced into EC8712 cells via retrovirus vector was capable of inhibiting cell proliferation and malignancy.

Animals↗
PubMed1992

Surgical approaches for improving the operating results of primary liver cancer.

The purpose of this study was to retrospectively analyse the results of 1102 primary liver cancer (PLC) patients who underwent liver resection in the past thirty years and to research some effective approaches for improving the longterm effect of PLC treatment. Ninety five percent were hepatocellular carcinoma (HCC), 85.2% with cirrhosis of hepatitis and 25.6% with tumor equal to or smaller than 5 cm in diameter. The mortality rate (MR) within 1 month after operation was 1.8%, the operative MR was 8.8% before 1977 and only 0.4% after that. The total 5-year survival rate (SR) was 28.4% while in the group of small tumor (less than or equal to 5 cm), it was 75.0%. Our experience is as follows: (1) Early diagnosis and early resection of PLC is the key point for improving the operative result of long-term survival. In 282 cases of small cancer, tumor resection rate was 90.0%. Of 48 cases with tumor equal to or smaller than 3 cm in diameter, the 5-year SR was 83.3%. (2) Rehepatectomy for recurrent liver cancer is an important approach for improving the surgical result. In our series, recurrent rate within 5 years postoperation was 72.3% in larger tumor group and 34.5% in small tumors. There were 78 cases undergoing reoperation in a total number of 170 times of rehepatectomy with 54.7% of 5-year SR, after the 1st operation and 34.6% after the 2nd one. (3) For unresectable large tumors, two-stage operation is an important development in liver surgery. We had 26 cases of such patients with 60.0% of 5-year SR. (4) Improvement of operating techniques plays an important role in reducing postoperative complications, lowering operative mortality and obtaining better operative result. (5) Postoperative comprehensive treatment is also important for solidating operative effect and preventing tumor recurrence.

Carcinoma, Hepatocellular↗