Biomedical subjects
Publications and source records attributed to M Wu.
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.
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.
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.
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.
In order to understand the clonal origins of recurrent hepatocellular carcinoma (HCC), as well as their clinical significance, the DNA contents of 44 resected recurrent HCCs from 21 patients were quantitatively measured using image analysis techniques. In 8 patients (38.1%), the recurrent HCCs had DNA contents which were obviously different from those in their primary tumors, suggesting new clonal origins; 13 (61.9%) had similar DNA contents, suggesting the same clonal origins. In these 2 groups, the mean intervals between 2 or 3 operations were 25 +/- 9.9 months and 7.9 +/- 3.1 months (P < 0.01), respectively, and the mean postoperative survival times were 51 +/- 20.8 months and 27.7 +/- 14.2 months (P < 0.05), respectively. The results indicate that the majority of recurrent HCCs originate from unresected fragments of their primary tumors, while some of them clearly originate from new tumor clones. Finally, reoperative resection is still considered an effective treatment for recurrent HCC, especially for those which originate from new tumor clones.
In order to study the changes in AFP reactive to lentil lectin (AFP-R-L) during the development of hepatocellular carcinoma (HCC) and its clinical significance, AFP-R-L was monitored in 64 patients by using 20-400 ng/L AFP and negative imaging localization. AFP-R-L was determined by using affino-crossed-immunoelectrophoresis autoradiography. AFP-R-L above 25% was considered positive for the diagnosis of HCC. Over a follow-up of 3-31 months, 32 patients developed HCC. The positivity of AFP-R-L was 59.4% in the HCC group at the first assay. The accuracy of using positive AFP-R-L values to predict HCC was 95.0%. Increased AFP-R-L levels appeared 3-24 months earlier than did positive imaging location. The results suggest that positive AFP-R-L values can predict the development of HCC.
For the purpose of detecting G2m(n) factor in human bloodstains, an ELISA inhibition test using mouse antihuman G2m(n) monoclonal antibody was established. The results revealed that the correctness rate for G2m(n) factor detection was 100%. The minimal amount of bloodstain required for detecting G2m(n) factor was 0.25 cm x 0.125 cm. This approach provided a new method for individual identification of human bloodstains.
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After sniffing of glue solvents (mixture of aliphatic hydrocarbons: boiling fraction 60-90 degrees C, ethylacetate and toluene) a blood alcohol concentration of 1.96 permille was indicated with an instrument using the infrared wavelength of 3.4 micrometer for the spectrophotometrical determination of breath alcohol. Testing of the individual solvents with a simple manual procedure showed linear relationships between concentrations in breathing air and the false positive breath alcohol values. Aliphatic hydrocarbons predominantly are responsible for the false positive breath alcohol determination. With 500 micrograms/liter a value of nearly 1.5 permille can be produced (using the factor of 2100 for the calculation of the blood alcohol concentration from breath alcohol). With ethylacetate or toluene up to 1 milligram/liter 0.5 permille ethanol in the blood will erroneously be found. The problem of recognition of crossreactive other gases by the measurement at two wavelengths (3.4 and 9.2 micrometer) is discussed.
P77PMC rat is a breed of rat with congenital audiogenic seizure (AS). AS attacks could be suppressed by cholecystokinin octapeptide (CCK-8) injected intracerebroventricularly (i.c.v.). In the present study we made i.c.v. injection of plasmid pSV2-beta Gal or pSV2-CCK encapsulated with lipofectin. Expression of pSV2-beta Gal in brain occurred from d 1 to d 14, with maximal expression at d 3 and d 4. After i.c.v. injection of pSV2-CCK plasmid, the AS of the P77PMC rats was markedly reduced, which was most obvious at d 3 and d 4. The time course of the AS repression was almost identical with that of pSV2-beta Gal expression. The results suggest that the repression of the AS in P77PMC rats is accounted for by the expression of foreign CCK gene in brain tissue.
In order to prepare human-mouse chimeric antibody against encephalitis type B virus, hybridoma 51-8 cells secreting monoclonal antibody against the virus were used as material for isolating heavy-chain variable region gene of the McAb. High molecular weight DNA of the hybridoma cell was partially digested by BamHI, and then constructed a gene library containing 2 x 10(7) pfu with lambda EMBL-3 as vector. With cDNA of heavy-chain variable region of the monoclonal antibody as probe, nine positive plaques were screened from 360,000 plaques, which have been proven that they contained a fragment of heavy-chain variable region genes by dot hybridization and Southern hybridization. Four recombinants among the nine positive plaques were further distinguished with J11 probe containing J3, J4 and heavy-chain enhancer. After cutting by EcoR1, there was a 3.8 kb fragment in three recombinants as similar to that in liver cell and Sp2/0 cell, but not in the fourth recombinant (lambda 8a4) which contained a 4.5 kb fragment that did not present in liver cell and Sp2/0 cell. The results showed that the inserts in former 3 recombinants were non-rearranged fragment of heavy-chain variable region genes, but the insert in lambda 8a4 contained a rearranged functional variable region gene. The 4.5 kb fragment could not be hybridized with a probe containing J1 and J2, but contained VH, J3 or/and J4 and enhancer, that further proved it was a functional variable region gene. Therefore, the 4.5 kb fragment was isolated and subcloned in pUC 19, and its physical map was made.(ABSTRACT TRUNCATED AT 250 WORDS)
Treatment of the human esophageal cancer cell line EC8712 with retinoic acid (RA) stopped the cell growth significantly and gave rise to terminal differentiation of the cells characterized by increased expression of involucrin gene. Two cDNA libraries were constructed from the parental and RA-treated cells respectively. Repeated subtractive hybridization of single-stranded plasmid DNA prepared from pooled colonies of cDNA library of the parental cells with cDNA probe generated from the RA-treated cells exhausted sequences common to both libraries of the cell. The unhybridized cDNA probe represented, therefore, the genes activated after RA-treatment. By using these enriched cDNAs as probe to screen the cDNA library constructed from the RA-treated cells thirty-nine positive colonies were obtained, of which two were specifically due to RA-induction. One of these two cDNA clones, designated as pRA538, has undergone further analysis and shown differentiation-inducing effect on parental cancer cells. A novel strategy for cloning genes involved in terminal differentiation of cancer cells is developed.
The nucleoid sedimentation test was used to analyse the DNA repair capacity in 35 members taken from 3 xeroderma pigmentosum (XP) families after their peripheral blood lymphocytes being exposed to UV irradiation or N-methyl-N-nitro-N-nitrosoguanidine (MNNG) at a dose of 2.5 microJ/mm2 and 2 micrograms/ml respectively. The results showed that the 6 XP patients all failed to repair their damaged DNA even after 20-hour incubation at 37 degrees C. The repair ratios were 0.61 +/- 0.13 for UV and 0.44 +/- 0.15 for MNNG while those of non-related normal members usually reached 0.96 +/- 0.07 and 0.71 +/- 0.07 for both UV and MNNG after 11-hour incubation. It is interesting to note that 9 obligatory heterozygotes (parents and grandparents of XP patients) and 4 highly possible heterozygotes (blood relatives of XP patients) also showed very poor DNA repair capacity: they could not accomplish their repair process even after 20-hour incubation. It has been showed that the nucleoid sedimentation test can probably be used to pick out the heterozygotes in XP families.
Mycobacterium avium complex infection is common in patients with AIDS. Experimentally infected mice have been treated successfully with azithromycin, a macrolide antibiotic. We report an uncontrolled phase I study in which male homosexuals with AIDS and M avium complex disease were given 500 mg azithromycin per day orally for 10, 20, or 30 days. Quantitative blood cultures showed a mean reduction in mycobacteraemia from 118 colony forming units (cfu)/ml to 43 cfu/ml in 3 patients treated for 10 days, and from 2028 cfu/ml to 136 cfu/ml in 21 patients treated for 20 or 30 days. Of the patients treated for 20 or 30 days, 15 of 21 with fever pretreatment and 12 of 18 with night sweats pretreatment reported resolution of these symptoms. The principal side-effects were loose stools or diarrhoea, but these did not result in cessation of therapy. Azithromycin, as a single oral agent, safely reduced M avium complex bacteraemia and associated symptoms in almost 75% of patients treated for at least 20 days. Further studies are needed to assess emergence of resistance.
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The interaction of the cholecystokinin octapeptide (CCK-8) with dopamine (DA) and dopamine agonists on neurons in the nucleus accumbens was investigated using single unit recording and iontophoretic techniques in urethane-anaesthetized rats. Neurons in the nucleus accumbens were activated by single pulse stimulation of amygdala. Using seven-barrel microelectrodes, the effects of iontophoretic application of CCK-8, DA, dopamine D1 and/or D2 receptor agonists (SKF 38393 and LY 171555 respectively) were compared. The iontophoretic application of DA, LY 171555 and LY 171555 + SKF 38393 attenuated by 50-60% the excitatory responses of accumbens neurons to electrical stimulation of basolateral amygdala whereas SKF 38393 attenuated the response by less than 30%. The iontophoretic application of CCK reduced these attenuating effects of DA, LY 171555 and SKF 38393 + LY 171555. With CCK there was a rather small reduction of the attenuating effect of SKF 38393. These observations provide additional electrophysiological evidence of the interaction of CCK and dopamine and suggest that the interaction is associated mainly with dopamine D2 mechanisms.
The TL region of the major histocompatibility complex of the mouse contains dozens of tandemly arranged class I genes, including those encoding the thymus leukemia (TL) antigens. TL antigens have been thought to be expressed only on the surface of some T lineage cells, namely immature thymocytes of some mouse strains (TL+ strains), some leukemia cells, and activated T cells. While the function of TL antigens is unknown, recent studies have implicated the products of at least some TL region class I genes as molecules that present antigens to gamma/delta T cells. Since some gamma/delta T cells are known to be specifically associated with certain epithelial tissues, we have investigated the expression of some TL region class I genes in a variety of epithelium-containing tissues. Our results show that the TL antigen gene of C57BL/6 mice, T3b, and the TL antigen genes of BALB/c mice, T3d (previously T3c) and T18d (previously T13c), are highly expressed in the epithelium of the small intestine. In the case of T3b, we further show, using a T3 product-specific antibody, that its product is expressed on the surface of the columnar epithelial cells. In addition, we demonstrated that two other TL region class I genes of C57BL/6 origin, T9b and T21b, are also expressed nearly exclusively in intestinal epithelial cells. These results are consistent with the hypothesis that the products of these TL region class I genes are recognized by gamma/delta T cell receptors of intestinal intraepithelial lymphocytes, a subset of gamma/delta T cells that is localized in the intestinal epithelium and has a restricted V gamma repertoire. Finally, our study indicates that the relative levels of expression of the two homologous TL antigen genes, T3d and T18d, differ widely between the thymus and the intestine.