A new subtype of HIV-1 gag sequence detected in Taiwan.
Explore the source record for details and available documents.
Adult↗
Biomedical subjects
K S Chang
Publications and source records attributed to K S Chang.
Propofol produces endothelium-independent vasodilation and may act as a Ca2+ channel blocker.
The mechanism of vasodilation induced by propofol was investigated using isolated rat thoracic aortic rings. Aortic rings were precontracted with potassium chloride (KCl) (40 mM) or phenylephrine (PE) (3 x 10(-8) to 3 x 10(-7) M) in the presence and absence of intact endothelium. Propofol produced similar concentration-dependent relaxation in aortic rings with and without endothelium regardless of whether they were precontracted with KCl or PE. The relaxation response to propofol was significantly greater in KCl-contracted aortic rings than in PE-contracted aortic rings. The propofol concentration producing 50% relaxation from the contracted state (RC50) was lower in aortic rings contracted with KCl than with PE, both with (5 +/- 0.6 x 10(-5) M vs 8.3 +/- 5.7 x 10(-4) M, P < 0.001) and without intact endothelium (3.9 +/- 0.5 x 10(-5) M vs 7.2 +/- 3.8 x 10(-4) M, P < 0.001). Propofol inhibited the Ca(2+)-induced contractions of aortic rings exposed to Ca(2+)-free media and depolarized with KCl (40 mM, 100 mM) in a dose-dependent manner. These effects are similar to those produced by verapamil. Propofol (5 x 10(-5) M) had minimal effect on the intracellular Ca2+ release elicited by PE (10(-5) M). We conclude that vasodilation produced by propofol is not endothelium-dependent but is likely due to blockade of voltage-gated influx of extracellular Ca2+.
Animals↗
Analysis of a new subtype of HIV-1 gag sequence from a case of vertical transmission in Taiwan.
A Taiwanese woman who lived with a presumably bisexual man of German nationality, and her infant daughter were found to be seropositive for HIV-1. From DNA preparations of peripheral blood mononuclear cells of the mother-infant pair, we amplified a segment, about 560 base pairs (bp), of gag portion of HIV-1 provirus by using polymerase chain reaction (PCR). The high degree of homology (94.7-97.5%) among clones (TM-1 and TM-2 from the mother, and TC-1 and TC-2 from the infant) of gag sequence provided a molecular epidemiological evidence for vertical transmission. However, these sequences exhibited lower degrees of homology (85.1-87.0%) with the corresponding gag segment of a North American HIV-1 subtype (HXB2), and that of a Zairean HIV-1 subtype (Z2Z6). The disparity of sequences between these Taiwanese clones and those of HXB2 and Z2Z6 was particularly prominent in the first (5' proximal) 200 bp, as shown by the low degree of homology (74.8-79.6%) when sequences of TM and TC clones which represented the first 200 bp were compared with those of HXB2 and Z2Z6. The sequence dissimilarity of these clones as compared with HXB2 manifested as transitions more frequently than transversions. Transitions involving G/A to A/G changes were more frequent than those involving T/C to C/T. Transversions involving G/A to T/C changes were slightly more frequent than those involving T/C to G/A changes for all clones except for TM-2 which showed an equal frequency. Presence of stop codons in each of the reading frames of these clones suggests that these may represent defective viral quasispecies. The deduced amino acid sequences from available open reading frames of these clones showed also distinct dissimilarities to HXB2 or Z2Z6. These findings indicate the presence of a gag subtype of HIV-1 which, according to the phylogenetic tree analysis, would represent a new subtype distinct from other known subtypes.
Adult↗
Molecular pathology of acute promyelocytic leukemia.
Explore the source record for details and available documents.
Cloning, Molecular↗
Expression of AML1-ETO fusion transcripts and detection of minimal residual disease in t(8;21)-positive acute myeloid leukemia.
The t(8;21) translocation breakpoint, which is observed in acute myeloid leukemia (AML), has recently been cloned and a fusion transcript identified. We have now designed primer sets capable of amplifying the breakpoint junction of the fusion transcript by the reverse transcription-polymerase chain reaction (RT-PCR). Primer set 821U/821D1 amplified a 200-bp DNA fragment, and primer set 821U/821D2 amplified a 1.2-kb DNA fragment in all t(8;21)-positive AML tested. Sequence analysis of the amplified DNA fragments demonstrated that all fusion transcripts were fused at exactly the same site, indicating that this translocation breakpoint occurs within a single intron of the AML1 and ETO genes. Forty-five cycles of RT-PCR were used to detect residual t(8;21)-positive leukemia cells in three patients who had been in complete remission for 1, 3 and 5 years. Minimal residual disease was found in all three samples. Northern blot analysis demonstrated that two fusion transcripts of 7 and 10 kb were expressed in the t(8;21)-positive AML and that the ETO gene is not normally expressed in the hematopoietic system. Expression of a normal 5.5-kb ETO mRNA was found in the lung. From these results we concluded that expression of the ETO gene in t(8;21)-positive AML was activated as a result of the translocation.
Base Sequence↗
Identification of breakpoints in t(8;21) acute myelogenous leukemia and isolation of a fusion transcript, AML1/ETO, with similarity to Drosophila segmentation gene, runt.
We have developed a restriction map of the chromosome 21 breakpoint region involved in t(8;21)(q22;q22.3) acute myelogenous leukemia (AML) and have isolated a genomic junction clone containing chromosome 8 and 21 material. Using probes from these regions, rearrangements have been identified in each of nine cases of t(8;21) AML examined. In addition, we have isolated cDNA clones from a t(8;21) AML cDNA library that contain fused sequences from chromosome 8 and 21. The chromosome 8 component, referred to as ETO (for eight twenty-one), is encoded over a large genomic region, as suggested by the analysis of corresponding yeast artificial chromosomes (YACs). The DNA sequence of the chromosome 21 portion of the fusion transcript is derived from the normal AML1 gene. A striking similarity (67% identity over 387 bp, with a corresponding 69% amino acid identity) was detected between AML1 and the Drosophila segmentation gene, runt. The critical consequence of the translocation is the juxtaposition of 5' sequences of AML1 to 3' sequences of ETO, oriented telomere to centromere on the der(8) chromosome.
Amino Acid Sequence↗
Specific expression of the annexin VIII gene in acute promyelocytic leukemia.
Since the translocation breakpoint t(15;17) (q22;q21) in acute promyelocytic leukemia (APL) occurs within the retinoic acid receptor-alpha (RARA) gene, the expression of many genes normally regulated by RARA may be affected by this translocation. To identify genes that may be aberrantly expressed in APL, a subtraction cDNA library of an APL patient with t(15;17) was constructed. A cDNA, pRD1, specifically expressed in APL was identified. DNA sequence analysis of pRD1 showed that this gene is similar to the DNA sequence of annexin VIII, a gene which encodes a vascular anticoagulant. The annexin VIII gene was assigned to chromosome 10, which indicates that specific expression of this gene in APL is not directly involved in the t(15;17) breakpoint region. We have analyzed the expression of annexin VIII gene in nine t(15;17)-positive APL patients and one APL patient with a chromosome 17q-abnormality. We found that all APL samples expressed high levels of the annexin VIII gene. Expression of the annexin VIII gene in all other leukemias, including acute myelogenous leukemia, chronic myelogenous leukemia, chronic lymphocytic leukemia, and acute lymphoblastic leukemia, was undetectable, except in one patient with acute myelogenous leukemia in which a very low level of expression was detected. Annexin VIII is highly expressed in the APL cell line, NB4. Its expression was significantly reduced after 8 hours of all-trans retinoic acid (ATRA) treatment, whereas the expression of RARA increased several-fold within 4 hours postinduction. Thus, increased expression of RARA preceded the downregulation of annexin VIII after ATRA induction, suggesting an inverse relationship between RARA and annexin VIII expression. Since increased expression of the fusion transcript was seen after ATRA induction and an APL without a t(15;17) translocation expressed high levels of annexin VIII, it appears that increased expression of annexin VIII in APL is not related to the fusion transcript. Therefore, dysregulation of the RARA gene may be related to the overexpression of annexin VIII in APL.
Amino Acid Sequence↗
The t(15;17) breakpoint in acute promyelocytic leukemia cluster within two different sites of the myl gene: targets for the detection of minimal residual disease by the polymerase chain reaction.
The retinoic acid receptor alpha (RAR alpha) and the myl gene are involved in the translocation breakpoint t(15;17)(q22;q21) in acute promyelocytic leukemia (APL). The majority of the breakpoint sites have been mapped within the second intron of the RAR alpha gene; however, the breakpoint sites on the myl gene are variable. Using primer sets derived from exon 2 or exon 3 of the RAR alpha gene and a primer derived from the myl cDNA, we were able to amplify the breakpoint sites of the fusion transcripts of all six APL RNA samples by the reverse transcriptase-polymerase chain reaction (RT-PCR). A DNA fragment of 290 bp (breakpoint A) was amplified using RNA samples from three patients, whereas two DNA fragments of 630 and 774 bp (breakpoint B) were amplified using RNA samples from the other three APL patients. DNA sequence analysis of the amplified fragments suggests that the APL breakpoints clustered within two different introns of the myl gene. Northern blot analysis demonstrated that fusion transcripts RAR alpha/myl and myl/RAR alpha of varying sizes were detected in patients with different breakpoint sites on the myl gene. In addition, we analyzed five APL samples in complete remission and detected t(15;17)-positive cells. We conclude that the t(15;17) breakpoints in APL can be amplified by PCR using a single primer set and that minimal residual disease can be demonstrated in APL using RT-PCR.
Base Sequence↗
L-asparaginase from developing seeds of Lupinus arboreus.
Asparaginase (EC 3.5.1.1) activity reached a maximum 40 days post anthesis in developing seeds of Lupinus arboreus and this correlated with the appearance of other ammonia assimilatory enzymes. Asparaginase, purified from these developing seeds, was resolved into three isoforms, designated asparaginases A, B and C. A major protein species in asparaginase A preparations co-focussed with enzyme activity on an isoelectric focussing gel. When analysed by SDS-PAGE, asparaginase isoforms A and B each yielded several polypeptides with M(r)s in the 14,000 to 19,000 ranged. These peptides are fragmentation products of an M(r) 36,000 asparaginase subunit. Polyclonal antibodies raised against asparaginase isoforms A and B precipitated asparaginase activity from a partially purified L. arboreus seed extract. Immunoaffinity chromatography recovered polypeptides with M(r)s between 14,000 and 19,000. Partial protein sequences were obtained for these asparaginase polypeptides.
Amino Acid Sequence↗
PCR amplification of chromosome-specific DNA isolated from flow cytometry-sorted chromosomes.
We have established a method for amplifying and obtaining large quantities of chromosome-specific DNA by linker/adaptor ligation and polymerase chain reaction (PCR). Small quantities of DNA isolated from flow cytometry-sorted chromosomes 17 and 21 were digested with MboI, ligated to a linker/adaptor, and then subjected to 35 cycles of PCR. Using this procedure, 20 micrograms of chromosome-specific DNA can be obtained. Southern blot analysis using several DNA probes previously localized to chromosomes 17 and 21 indicated that these gene sequences were present in the amplified chromosome-specific DNA. A small quantity of the chromosome-specific DNA obtained from the first round of PCR amplification was used to amplify DNA for a second, third, and fourth round of PCR (30 cycles), and specific DNA sequences were still detectable. Fluorescence in situ hybridization using these chromosome-specific DNA probes clearly indicated the hybridization signals to the designated chromosomes. We showed that PCR-amplified chromosome 17-specific DNA can be used to detect nonrandom chromosomal translocation of t(15;17) in acute promyelocytic leukemia by fluorescence in situ hybridization.
Base Sequence↗
China's rural reform: the state and peasantry in constructing a macro-rationality.
As a critique of the popular perspective on China's rural reform centered on microinstitutional problems of collective farming such as work incentive and monitoring, this paper places an alternative emphasis on the distinct organizational characteristics of the peasant family in production, distribution, and welfare. What the Chinese state saw in family-based peasantry was not a typical market-oriented private economy operating mainly in pursuit of short term profits, but a multipurpose, morally governed unit in which the rural population maintains stable work relations, pursues diverse entrepreneurial activities, and satisfies basic subsistence needs; i.e., a organizational unit which could take over most of the social and economic functions of the pre-reform collective. In a sense, China's rural decollectivization has been a process of deceptively transferring the burden of absorbing and supporting the huge rural surplus labor to individual peasant families for whose economic activities the state is not directly responsible.
Agriculture↗
Endothelium-dependent increase in vascular sensitivity to phenylephrine in long-term streptozotocin diabetic rat aorta.
1. The effect of short- and long-term streptozotocin (STZ)-induced diabetes (12 and 52 weeks) on the vascular response to phenylephrine was examined in the isolated thoracic aorta with and without intact endothelium from diabetic, age matched control rats and diabetic rats treated with insulin. 2. Twelve weeks after induction of diabetes, aortae with intact endothelium demonstrated no changes either in sensitivity (defined as pD2) or contractility (defined as the maximal developed tension per aortic tissue wet weight) to phenylephrine. 3. In contrast, 52 weeks after induction of diabetes, aortae with intact endothelium demonstrated an increased sensitivity to phenylephrine while contractility to phenylephrine was not changed. Insulin treatment partially corrected the increased sensitivity to phenylephrine observed in diabetic rat aorta. 4. Removal of endothelium abolished the difference in phenylephrine sensitivity between diabetic and control aortae at 52 weeks. 5. Pretreatment of intact aortae with methylene blue, an inhibitor of endothelium-derived relaxing factor (EDRF), abolished the difference in phenylephrine sensitivity between control and diabetic rat aortae at 52 weeks, while pretreatment with indomethacin, an inhibitor of cyclo-oxygenase, had no effect. These results suggest that decreases in production or release of EDRF might be responsible for the increased vascular sensitivity to phenylephrine observed in long-term STZ diabetic rats. 6. Acetylcholine-induced relaxation, which is EDRF-dependent, was less in diabetic rat aortae with intact endothelium at 52 weeks, but not at 12 weeks. These results further support the theory that decreases in capacity of the endothelium to synthesize or release EDRF may occur in long-term STZ diabetic rats.
Acetylcholine↗
Characterization of a fusion cDNA (RARA/myl) transcribed from the t(15;17) translocation breakpoint in acute promyelocytic leukemia.
A nonrandom chromosomal translocation breakpoint, t(15;17)(q22;q21), is found in almost all patients with acute promyelocytic leukemia (APL). Most of these breakpoints occur within the second intron of the retinoic acid receptor-alpha (RARA) gene. We screened a cDNA library of APL and have identified and sequenced a cDNA transcribed from the t(15;17) translocation breakpoint. The 5' end of cDNA p1715 consists of 503 bp of the RARA exon II sequence. A 1.76-kb cDNA without homology to any known gene available in GenBank was found truncated downstream. This cDNA sequence was assigned to chromosome 15 by dot blot hybridization of the flow cytometry-sorted chromosomes. We designate this fusion cDNA RARA/myl, which is different from myl/RARA reported by de The et al. (H. de The, C. Chomienne, M. Lanotte, L. Degos, and A. Dejean, Nature (London) 347:558-561, 1990). This result demonstrates that the two different types of hybrid mRNA can be transcribed from this breakpoint. We screened a non-APL cDNA library and identified a 2.8-kb myl cDNA. This cDNA is able to encode a polypeptide with a molecular weight of 78,450. Alternative splicing of the myl gene which resulted in myl proteins with different C terminals was found. Southern blot analysis of the genomic DNA isolated from 17 APL patients by using the myl DNA probe demonstrated that the myl gene in 12 samples was rearranged. Northern (RNA) blot analysis of RARA gene expression in two APL RNA samples showed abnormal mRNA species of 4.2 and 3.2 kb in one patient and of 4.8 and 3.8 kb in another patient; these were in addition to the normal mRNA species of 3.7 and 2.7-kb. The myl DNA probe detected a 2.6-kb abnormal mRNA in addition to the normal mRNA species of 3.2, 4.2, and 5.5 kb. Using the polymerase chain reaction, we demonstrated that both RARA/myl and myl/RARA were coexpressed in samples from three different APL patients. From this study, we conclude that the t(15;17) translocation breakpoint results in the transcription of two different fusion transcripts which are expected to be translated into fusion proteins.
Amino Acid Sequence↗
Alterations in cardiac parasympathetic indices in STZ-induced diabetic rats.
Autonomic neuropathy involving parasympathetic innervation is a complication of diabetes mellitus. Biochemical and morphological indices of the parasympathetic innervation of the heart were investigated in rats after diabetes mellitus was induced with streptozocin (STZ). Choline acetyltransferase (CAT) activity was used as a biochemical marker for parasympathetic innervation. Total CAT activity within the hearts of diabetic rats was unchanged after 1 and 2 wk of diabetes and was significantly reduced after 4, 8, and 12 wk. Morphological changes within the cardiac portion of the parasympathetic innervation were assessed at 8 wk when CAT activity was decreased. In diabetic rats, there was a reduction in both cardiac ganglion cell size and number. In contrast, in insulin-treated STZ-induced diabetic rats, ganglion cells were similar in size and number to those in a control group given 3-O-methylglucose to prevent induction of diabetes mellitus by STZ. Thus, diabetes mellitus is associated with alterations in cardiac parasympathetic innervation in rats, and supplemental insulin protects against these changes. These alterations may contribute to impaired parasympathetic neural control of the heart in diabetes mellitus.
Analysis of Variance↗
A vertically transmitted HIV-1 gag-subtype variant detected in Taiwan.
We used polymerase chain reaction (PCR) to amplify a segment, about 560 base pairs (bp), of HIV-1 gag DNA prepared from peripheral blood mononuclear cells of a seropositive Taiwanese pair of mother and infant. TM-1 and TC-1 clones of PCR-amplified DNA derived from the mother and infant, respectively, showed a 94.5% homology with each other. However, the TM-1 and TC-1 sequences exhibited lower degrees of homology, i.e. only 85.1% and 85.8%, respectively, with the corresponding gag segment of a North American HIV-1 subtype (HXB2), and 86.4% and 87.0%, respectively, with that of a Zairean HIV-1 subtype (Z2Z6). The divergence of TM-1 and TC-1 sequences from those of HXB2 and Z2Z6 is particularly prominent in the first (5' proximal) 200 bp of the cloned DNA segment, involving transitions more frequently than transversions. Two additional clones TM-2 and TC-2 derived from the mother and infant were sequenced for the first 200 bp. These four clones showed a high degree of homology (94.7-97.5%) among themselves, providing an evidence for transmission of the virus from the mother to the infant. These findings show the epidemiological value of PCR, and indicate the presence of a gag subtype of HIV-1 which is distinct from both the North American and Zairean subtypes according to the phylogenetic tree constructed.
Adult↗
Status and trend of HIV-1 infection and AIDS in Taiwan, December, 1991.
From May 1, 1985 to December 31, 1991, a total of 4,962,707 serum samples from 8 population groups in Taiwan were tested for anti-human immunodeficiency virus type 1 (anti-HIV-1). In total, 256 samples were seropositive; of these individuals, 43 developed acquired immunodeficiency syndrome (AIDS): 29 were homosexuals; 5 were hemophiliacs; 8 were heterosexuals and 1 was of unknown risk. Although the prevalence of HIV-1 infection and AIDS remains low compared with other countries, since 1988 the increase has been rapid. Before 1977 the majority were homosexuals and hemophiliacs; thereafter the risk groups diversified, with a trend away from homosexuals and hemophiliacs towards heterosexuals and intravenous drug abusers (IVDAs). A few patients have caused serious social problems for the public, health care workers and families. Active community efforts are needed to achieve future success in the control of HIV-1 infection and AIDS in Taiwan.
Acquired Immunodeficiency Syndrome↗
Regulation of cellular trans-activating activities in two different promonocytic leukemia cell lines.
Trans-activating activities of certain cellular promoter/enhancer genes may reflect the underlying mechanism for cellular differentiation. We have used two promonocytic leukemia cell lines, U937 and HL-CZ, which differ in their differentiation antigen expression. While both cell lines express CD15 antigen, only the former expresses both CD4 and CD10 antigens. These phenotypes suggest that these two cell lines appear to be arrested at different stages of differentiation. Some regions of the long terminal repeat (LTR) of human immunodeficiency virus-1 (HIV-1) contain nucleotide sequences which bind cellular trans-activating factors such as NF-kappa B and Sp1. These sequences are also present in cellular regulatory gene sequences. The cell lines have been transfected by electroporation with a nested series of deletion mutants containing different lengths of the promoter/enhancer region for HIV-LTR. The promoter/enhancer region has been linked to a 'reporter' chloramphenicol acetyl transferase (CAT) gene. We have found that promoter/enhancer trans-activation is markedly enhanced by treating transfected cells with 12-O-tetradecanoylphorbol-13-acetate (TPA), while similar treatment with tumor necrosis factor-alpha (TNF alpha) slightly enhanced activation. U937 cells always showed much greater transactivating activities than did HL-CZ cells. Deletion of a negative regulatory element (NRE) from the LTR resulted in an enhanced transactivation, while deletions affecting NF-kappa B and/or Sp1 binding sites markedly reduced transactivation. Deletion of both NRE and NRF, a second negative regulatory factor binding site, from the LTR restored the transactivation. However, in the presence of TPA, deletion of NRE sequence without concomitant deletion of the downstream NRF binding sequence was sufficient for recovering transactivation. Since these two cell lines have shown subtle differences in these responses, it may be speculated that monocytes at different stages of differentiation may respond in different ways, qualitatively and/or quantitatively, to signal transduction factors involved in the transactivation of cellular genes.
Antigens, Differentiation↗
Influence of amineptine on changes of blood pressure evoked by norepinephrine and dopamine.
The influence of amineptine, an antidepressant currently employed having mainly selective dopaminergic neurochemical activity, on the pressor responses evoked by norepinephrine (NE) and dopamine (DA) was studied in anesthetized whole rats. Amineptine at doses of 0.5, 1.5, and 5.0 mg/kg/30 min infused into the femoral vein of the rat caused a dose-related inhibition of the pressor responses of NE and DA. The hypertensive responses of NE and DA augmented by pretreatment with reserpine, a catecholamine depletor, were also clearly depressed following the infusion of amineptine with a rate of 1.5 mg/kg/30 min. Furthermore, the pressor responses of NE and DA potentiated by pretreatment with debrisoquin, a sympathetic neuron blocker, were markedly diminished after pretreatment with the infusion of amineptine at the above same rate (1.5 mg/kg/30 min). These experimental results demonstrate that amineptine causes an inhibitory effect on the pressor responses evoked by NE and DA. It is thought that the amineptine effect may be due to the blockade of the peripheral adrenergic alpha-receptors in addition to the previously described uptake inhibition of dopamine.
Animals↗