Search PubMed⌕ Search

Biomedical subjects

Y Yang

Publications and source records attributed to Y Yang.

At least 145 records · Page 8Linked to original sources
PubMed2001

Identification of a calcium/calmodulin-dependent protein kinase that phosphorylates the Neurospora circadian clock protein FREQUENCY.

Phosphorylation of circadian clock proteins represents a major regulatory step that controls circadian clocks. In Neurospora, the circadian clock protein FREQUENCY (FRQ) is progressively phosphorylated over time, and its level decreases when it is hyperphosphorylated. In this study, we showed that most of the kinase activity phosphorylating FRQ in vitro was calcium/calmodulin-dependent, and the endogenous FRQ in the Neurospora extracts was phosphorylated by a Ca/CaM-dependent kinase-like activity. From Neurospora cell extracts, an approximately 50-kDa Ca/CaM-dependent kinase (CAMK-1) that can specifically phosphorylate FRQ was purified. In vitro, this kinase accounts for near half of the FRQ kinase activity, and it can phosphorylate the FRQ region that contains the three known functionally important phosphorylation sites. To understand the function of camk-1 in vivo, it was disrupted in Neurospora by gene replacement. After germination from ascospores, the camk-1 null strains grew slowly, indicating that CAMK-1 plays an important role in growth and development of Neurospora. This phenotype was transient however, revealing redundancy in the system. Analysis of the camk-1 null strain revealed that the deletion of camk-1 affected phase, period, and light-induced phase shifting of the circadian conidiation rhythm. Taken together, our results suggest that multiple kinases may phosphorylate FRQ in vivo.

Amino Acid Sequence↗
PubMed2001

Accelerated metabolism and exclusion of 4-hydroxynonenal through induction of RLIP76 and hGST5.8 is an early adaptive response of cells to heat and oxidative stress.

To explore the role of lipid peroxidation (LPO) products in the initial phase of stress mediated signaling, we studied the effect of mild, transient oxidative or heat stress on parameters that regulate the cellular concentration of 4-hydroxynonenal (4-HNE). When K562 cells were exposed to mild heat shock (42 degrees C, 30 min) or oxidative stress (50 microM H2O2, 20 min) and allowed to recover for 2 h, there was a severalfold induction of hGST5.8, which catalyzes the formation of glutathione-4-HNE conjugate (GS-HNE), and RLIP76, which mediates the transport of GS-HNE from cells (Awasthi, S., Cheng, J., Singhal, S. S., Saini, M. K., Pandya, U., Pikula, S., Bandorowicz-Pikula, J., Singh, S. V., Zimniak, P., and Awasthi, Y. C. (2000) Biochemistry 39, 9327-9334). Enhanced LPO was observed in stressed cells, but the major antioxidant enzymes and HSP70 remained unaffected. The stressed cells showed higher GS-HNE-conjugating activity and increased efflux of GS-HNE. Stress-pre-conditioned cells with induced hGST5.8 and RLIP76 acquired resistance to 4-HNE and H2O2-mediated apoptosis by suppressing a sustained activation of c-Jun N-terminal kinase and caspase 3. The protective effect of stress pre-conditioning against apoptosis was abrogated by coating the cells with anti-RLIP76 IgG, which inhibited the efflux of GS-HNE from cells, indicating that the cells acquired resistance to apoptosis by metabolizing and excluding 4-HNE at a higher rate. Induction of hGST5.8 and RLIP76 by mild, transient stress and the resulting resistance of stress-pre-conditioned cells to apoptosis appears to be a general phenomenon since it was not limited to K562 cells but was also evident in lung cancer cells, H-69, H-226, human leukemia cells, HL-60, and human retinal pigmented epithelial cells. These results strongly suggest a role of LPO products, particularly 4-HNE, in the initial phase of stress mediated signaling.

ATP-Binding Cassette Transporters↗
PubMed2001

Reactions of tetrakis(dimethylamide)-titanium, -zirconium and -hafnium with silanes: synthesis of unusual amide hydride complexes and mechanistic studies of titanium-silicon-nitride (Ti-Si-N) formation.

M(NMe(2))(4) (M = Ti, Zr, Hf) were found to react with H(2)SiR'Ph (R' = H, Me, Ph) to yield H(2), aminosilanes, and black solids. Unusual amide hydride complexes [(Me(2)N)(3)M(mu-H)(mu-NMe(2))(2)](2)M (M = Zr, 1; Hf, 2) were observed to be intermediates and characterized by single-crystal X-ray diffraction. [(Me(2)N)(3)M(mu-D)(mu-NMe(2))(2)](2)M (1-d(2), 2-d(2)) were prepared through reactions of M(NMe(2))(4) with D(2)SiPh(2). Reactions of (Me(2)N)(3)ZrSi(SiMe(3))(3) (5) with H(2)SiR'Ph were found to give aminosilanes and (Me(2)N)(2)Zr(H)Si(SiMe(3))(3) (6). These reactions are reversible through unusual equilibria such as (Me(2)N)(3)ZrSi(SiMe(3))(3) (5) + H(2)SiPh(2) right arrow over left arrow (Me(2)N)(2)Zr(H)Si(SiMe(3))(3) (6) + HSi(NMe(2))Ph(2). The deuteride ligand in (Me(2)N)(2)Zr(D)Si(SiMe(3))(3) (6-d(1)) undergoes H-D exchange with H(2)SiR'Ph (R' = Me, H) to give 6 and HDSiR'Ph. The reaction of Ti(NMe(2))(4) with SiH(4) in chemical vapor deposition at 450 degrees C yielded thin Ti-Si-N ternary films containing TiN and Si(3)N(4). Ti(NMe(2))(4) reacts with SiH(4) at 23 degrees C to give H(2), HSi(NMe(2))(3), and a black solid. HNMe(2) was not detected in this reaction. The reaction mixture, upon heating, gave TiN and Si(3)N(4) powders. Analyses and reactivities of the black solid revealed that it contained -H and unreacted -NMe(2) ligands but no silicon-containing ligand. Ab initio quantum chemical calculations of the reactions of Ti(NR(2))(4) (R = Me, H) with SiH(4) indicated that the formation of aminosilanes and HTi(NR(2))(3) was favored. These calculations also showed that HTi(NH(2))(3) (3b) reacted with SiH(4) or H(3)Si-NH(2) in the following step to give H(2)Ti(NH(2))(2) (4b) and aminosilanes. The results in the current studies indicated that the role of SiH(4) in its reaction with Ti(NMe(2))(4) was mainly to remove amide ligands as HSi(NMe(2))(3). The removal of amide ligands is incomplete, and the reaction thus yielded "=Ti(H)(NMe(2))" as the black solid. Subsequent heating of the black solid and HSi(NMe(2))(3) may then yield TiN and Si(3)N(4), respectively, as the Ti-Si-N materials.

Journal Article↗
PubMed2001

Anticancer properties for 4,4'-dihydroxybenzophenone-2,4-dinitrophenylhydrazone (A-007)/3,7-diaminophenothiazin-5-ium double salts.

4,4'-Dihydroxybenzophenone-2,4-dinitrophenylhydrazone (A-007) formed stable double salts with phenothiazin-5-ium salts (2a-d), which have improved in vitro anticancer activities, as compared to A-007 alone. The stable salt between methylene blue (2a) and A-007 allowed the latter to diffuse into the dermis layers of skin. It is anticipated that these new salts will allow A-007 to penetrate into the deep lymphatic/vascular channels of the dermis, which contain metastatic cancer cells, and improve in vivo anticancer activities.

Administration, Cutaneous↗
PubMed2001

Identification and characterization of a novel androgen receptor coregulator ARA267-alpha in prostate cancer cells.

The androgen receptor (AR) is a member of the steroid receptor superfamily that binds to the androgen response element to regulate target gene transcription. AR may need to interact with some selected coregulators for maximal or proper androgen function. Here we report the isolation of a new AR coregulator with a calculated molecular mass of 267 kDa named the androgen receptor-associated protein 267-alpha (ARA267-alpha). ARA267-alpha contains 2427 amino acids, including one Su(var)3-9, Enhancer-of-zeste, and Trithorax (SET) domain, two LXXLL motifs, three nuclear translocation signal (NLS) sequences, and four plant homeodomain (PHD) finger domains. Northern blot analyses reveal that ARA267-alpha is expressed predominantly in the lymph node as 13- and 10-kilobase transcripts. HepG2 is the only cell line tested that does not express ARA267-alpha. Yeast two-hybrid and glutathione S-transferase pull-down assays show that both the N and C terminus of ARA267-alpha interact with the AR DNA- and ligand-binding domains. Unlike other coregulators, such as CBP, which enhance the interaction between the N and C terminus of AR, we found that ARA267-alpha had little influence on the interaction between the N and C terminus of AR. Luciferase and chloramphenicol acetyltransferase assays show that ARA267-alpha can enhance AR transactivation in a dihydrotestosterone-dependent manner in PC-3 and H1299 cells. ARA267-alpha can also enhance AR transactivation with other coregulators, such as ARA24 or PCAF, a histone acetylase, in an additive manner. Together, our data demonstrate that ARA267-alpha is a new AR coregulator containing the SET domain with an exceptionally large molecular mass that can enhance AR transactivation in prostate cancer cells.

Amino Acid Sequence↗
PubMed2001

Transfection of mGSTA4 in HL-60 cells protects against 4-hydroxynonenal-induced apoptosis by inhibiting JNK-mediated signaling.

The mammalian alpha-class glutathione S-transferase (GST) isozymes mGSTA4-4, rGSTA4-4, and hGSTA4-4 are known to utilize 4-hydroxynonenal (4HNE) as a preferred substrate. During the present studies, we have examined the effect of transfecting human myeloid HL-60 cells with mGSTA4, on 4-HNE-induced apoptosis and the associated signaling mechanisms. Results of these studies show that treatment of the wild-type or vector-only-transfected HL-60 cells with 20 microM 4-HNE caused apoptosis within 2 h. The cells transfected with mGSTA4 did not undergo apoptosis under these conditions even after 4 h. In the wild-type and vector-transfected cells, apoptosis was preceded by JNK activation and c-Jun phosphorylation within 30 min, and an increase in AP-1 binding within 2 h of treatment with 20 microM 4-HNE. In mGSTA4-transfected cells, JNK activation and c-Jun phosphorylation were observed after 1 h, and increased AP-1 binding was observed after 8 h under these conditions. In the control cells, 20 microM 4-HNE caused caspase 3 activation and poly(ADP-ribose) polymerase cleavage within 2 h, while in mGSTA4-transfected cells, a lesser degree of these effects was observed even after 8 h. Transfection with mGSTA4 also provided protection to the cells from 4-HNE and doxorubicin cytotoxicity (1.6- and 2.6-fold, respectively). These results show that 4-HNE mediates apoptosis through its effects on JNK and caspase 3, and that 4-HNE metabolizing GST isozyme(s) may be important in the regulation of this pathway of oxidative-stress-induced apoptosis.

Aldehydes↗
PubMed2001

[Comparative effects of carvediol in large, middle, and small dose in preventing left ventricular remodeling after acute myocardial infarction in rats].

OBJECTIVE: To compare the effects of carvedilol in large, middle, or small dose in preventing left ventricular remodeling (LVRM) after acute myocardial infarction (AMI) in rats. METHODS: AMI were conducted by ligating left coronary artery in female SD rats. Twenty-four hours after the procedure, 142 surviving rats were randomly assigned to one of the following groups: AMI control (n = 35), large dose carvedilol (10 mg.kg-1.d-1, n = 37), middle dose carvediol (1 mg.kg-1.d-1, n = 35), and small dose carvediol(0.1 mg.kg-1.d-1, n = 35) Sham-operated rats (n = 16) were selected randomly as non-infarction control. Carvedilol was administered by direct gastric gavage for four weeks. Then hemodynamic studies were performed, and the hearts of the rats were taken out and fixed with 10% formalin and pathologic analysis was performed. Exclusive of the rats with infarct size < 35% or > 55%, complete experimental variables were obtained in 58 rats. RESULTS: No significant difference was found in MI size (44.5-46.3%, all P > 0.05) among the four AMI groups. Compared with the sham-operated group, a significant increase could be seen in left ventricular end diastolic pressure (LVEDP, 24.5 mm Hg +/- 5.3 mm Hg), left ventricular volume (LVV, 0.92 ml +/- 0.11 ml), left ventricular absolute weight (LVAW, 730 mg +/- 79 mg) and left ventricular relative weight (LVRW) (LVEDP: vs.; LVV: vs.; LVAW: vs. 730 mg +/- 79 mg; P < 0.05-0.001), and a significant decrease could be seen in sphericity index and LV pressure maximal rate of rise and fall (+/- dp/dt) as well as their corrected values (+/- dp/dt/LVSP) among AMI groups (P < 0.01-0.001). In comparison with AMI groups, a dose-dependent and significant decrease could be seen in LVEDP (7.7 mm Hg +/- 1.9 mm Hg, 12.1 mm Hg +/- 2.0 mm Hg, 14.5 mm Hg +/- 4.6 mm Hg), LVV(0.72 ml +/- 0.10 ml, 0.79 ml +/- 0.08 ml, 0.82 ml +/- 0.10 ml), LVAW (589 mg +/- 57 mg, 622 mg +/- 70 mg, 666 mg +/- 57 mg) and LVRW among large, middle, and small dose carvediol groups (all P < 0.01), while a significant increase could be seen in +/- dp/dt and +/- dp/dt/LVSP (all P < 0.05-0.01) among the three carvedilol groups without significant difference among different doses. The sphericity index was significantly increased only in large-dose carvedilol group (1.71 +/- 0.19 vs 1.96 +/- 0.25, P < 0.05). CONCLUSION: Carvedilol in no matter what dose effectively and dose-dependently prevent LV remodeling after AMI and improve hemodynamics and LV function in rats.

Adrenergic beta-Antagonists↗
PubMed2001

Reduction of ENU-induced transversion mutations by the isoflavone genistein in Escherichia coli.

In studies of mutagenesis induced by the carcinogen N-ethyl-N-nitrosourea (ENU) in the bacterium Escherichia coli FX-11, it was observed that G:C to A:T transitions did not require the inducible umuDC gene products, while a portion of the A:T to G:C transitions and all transversion mutations were dependent on a functional umuC gene. This observation suggested that the different base substitutions may result from differential processing of specific DNA adducts produced by ENU. To further understand these processes, we have investigated the effect of the soybean isoflavone genistein on the production of ENU-induced mutations. This compound, in particular, has been shown to exhibit numerous effects including the inhibition of the growth or proliferation of a variety of cancers, inhibition of angiogenesis, inhibition of tyrosine protein kinases and anti-oxidant properties. In our experiments, tyrosine defective (TyrA(-)) E. coli were exposed to ENU and a portion of the ENU-treated cells were exposed to genistein. The results showed a three-fold reduction in the overall mutation frequency when cells were treated with genistein subsequent to ENU-exposure and this anti-mutagenic effect was dependent on the dose of genistein employed. However, only certain types of base substitution mutagenesis were affected. In particular, transversion mutations were reduced an average of about 8.5-fold, while transitions were not greatly affected. In addition, UV-mutagenesis was reduced about three-fold and induction of the SOS response (as monitored with a sulA-lacZ fusion) was decreased. These results suggest that genistein may interfere with expression of the SOS response, including the UmuC-mediated lesion bypass mechanism that is necessary for UV-mutagenesis and the generation of transversions by ENU in E. coli.

Alkylating Agents↗
PubMed2001

Genetics of human complement component C4 and evolution the central MHC.

The two classes of human complement component C4 proteins C4A and C4B manifest differential chemical reactivities and binding affinities towards target surfaces and complement receptor CR1. There are multiple, polymorphic allotypes of C4A and C4B proteins. A complex multiplication pattern of C4A and C4B genes with variations in gene size, gene dosage and flanking genes exists in the population. This is probably driven by the selection pressure to respond to a great variety of parasites efficiently and effectively, which the bony fish achieved through the multiplication and diversification of the related complement C3 proteins. Complement C4, C3 and C5 belong to the alpha2 macroglobulin protein family but acquired specific features that include an anaphylatoxin domain, a netrin (NTR) domain, and stretches of basic residues for proteolytic processings to form multiple chain structures. Complement C3 and C4 are important in the innate immune response as they opsonize parasites for phagocytosis. The emergence of complement C3 predates proteins involved in the adaptive immune response as C3 is present in deuterostome invertebrates such as echinoderms. The human C4 genes are located in the central MHC at chromosome 6p21.3. C3 and C5 are located at chromosome 19 and 9, respectively, with representatives of the other groups of genes paralogous to the MHC at 19p13.1-p13.3, 1q21-25, and 9q33-34. The central MHC also contains genes for complement components C2 and Bf. These genes appear to have similar evolutionary histories to C3/C4/C5 and are used here to illustrate stepwise processes resulting in co-location of diverse domains, chromosomal duplication, local segmental duplication and divergence of sequence and function. This model of evolution is useful in the investigation of innate and acquired immunity and in seeking explanations for diseases associated with MHC ancestral haplotypes.

Amino Acid Sequence↗
PubMed2001

Identification of a mouse thiamine transporter gene as a direct transcriptional target for p53.

p53 tumor suppressor is a transcription factor that functions, in part, through many of its downstream target genes. We have identified a p53-inducible gene by performing mRNA differential display on IW32 murine erythroleukemia cells containing a temperature-sensitive p53 mutant allele, tsp53(Val-135). Sequence analysis of the full-length cDNA revealed its identity as the mouse homologue of the human thiamine transporter 1 (THTR-1). Induction of the mouse THTR-1 (mTHTR-1) mRNA was detectable as early as 1 h at 32.5 degrees C; upon shifting back to 38.5 degrees C, mTHTR-1 transcript was rapidly degraded with a half-life of less than 2 h. Elevation of mTHTR-1 expression was found in DNA damage-induced normal mouse embryonic fibroblast cells, but not in p53(-/-) mouse embryonic fibroblast cells, suggesting that mTHTR-1 induction was p53-dependent. A region within the first intron of the mTHTR-1 gene bound to p53 and conferred the p53-mediated transactivation. Furthermore, increased thiamine transporter activities were found in cells overexpressing mTHTR-1 and under conditions of DNA damage or p53 activation. Our findings indicate that p53 may be involved in maintaining thiamine homeostasis through transactivation of THTR-1.

Amino Acid Sequence↗
PubMed2001

RLIP76 is the major ATP-dependent transporter of glutathione-conjugates and doxorubicin in human erythrocytes.

We have recently demonstrated that RLIP76, a Ral-binding GTPase activating protein mediates ATP-dependent transport of glutathione (GSH) conjugates of electrophiles (GS-E) as well as doxorubicin (DOX), and that it is identical with DNP-SG ATPase, a GS-E transporter previously characterized by us in erythrocyte membranes (Awasthi et al. Biochemistry 39, 9327-9334). Multidrug resistance-associated protein (MRP1) belonging to the family of the ABC-transporters has also been suggested to be a GS-E transporter in human erythrocytes. Using immunological approaches, the present studies were designed to elucidate the relative contributions of RLIP76, MRP1, and P-glycoprotein (Pgp), in the ATP-dependent transport of GS-E and DOX in human erythrocytes. In Western blot analyses using antibodies against RLIP76, a strong expression of RLIP76 was observed in erythrocytes. Immunohistochemical studies using a fluorescent probe showed association of RLIP76 with erythrocyte membrane, which was consistent with its transport function. Neither MRP1 nor Pgp were detected in erythrocytes when the antibodies against MRP1 or Pgp were used. In erythrocyte inside-out vesicles (IOVs) coated with antibodies against RLIP76, a dose-dependent inhibition of the ATP-dependent transport of DOX and GS-E, including S-(dinitrophenyl)glutathione (DNP-SG), leukotriene C(4), and the GSH conjugate of 4-hydroxynonenal, was observed with a maximal inhibition of about 70%. On the contrary, in the IOVs coated with the antibodies against MRP1 or Pgp no significant inhibition of the ATP-dependent transport of these compounds was observed. These findings suggest that RLIP76 is the major ATP-dependent transporter of GS-E and DOX in human erythrocytes.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2001

Intracellular trafficking determinants in APOBEC-1, the catalytic subunit for cytidine to uridine editing of apolipoprotein B mRNA.

The posttranscriptional deamination editing of apolipoprotein B (apoB) mRNA catalyzed by APOBEC-1 (apoB mRNA editing catalytic subunit 1) is a nuclear process. The signals in APOBEC-1 responsible for its dual cytoplasmic/nuclear distribution have been evaluated. Residues 97-172 in the middle of APOBEC-1 together with its N-terminal 56 residues affect nuclear localization. Mutagenesis studies however revealed no discrete nuclear localization signal in APOBEC-1. Fifteen amino acids (Leu 173-Leu 187) within the previously identified C-terminal domain of APOBEC-1 were sufficient as a determinant for cytoplasmic distribution in that context. These residues failed to demonstrate nuclear export function in a reporter assay. Further, the distribution of APOBEC-1 in the cytoplasm did not respond to leptomycin B, suggesting that APOBEC-1 did not have nuclear export activity. The data suggested that there are at least three regions in APOBEC-1 that participate in its distribution in both the nucleus and the cytoplasm of editing competent cells; however, none of these meet the functional criteria of nuclear localization or nuclear export signals. The findings are discussed in terms of their implications in the regulation of nuclear editing activity and the possibility that interactions with chaperones may play a role in the cellular distribution of APOBEC-1.

APOBEC-1 Deaminase↗
PubMed2001

[Pattern reversal visual evoked potentials analysis in patients with noninsulin-dependent diabetes mellitus].

OBJECTIVE: To explore the alteration of pattern reversal visual evoked potentials (PVEPs) in patients with noninsulin-dependent diabetes mellitus (NIDDM) and its values in clinical application. METHODS: PVEPs were recorded in 30 cases with NIDDM and 30 cases of normal individuals. RESULTS: The abnormal rate of PVEPs in patients with NIDDM was 58.33%, and the latency of P100 was markedly prolonged. The wave-forms were poor-differentiated, and the amplitudes of waves were low. CONCLUSION: Abnormal PVEPs can be regarded as one of the index of visual function in patients with NIDDM. The abnormality of PVEPs is related to blood sugar in empty stomach, course of NIDDM. peripheral nerve lesions and diabetic retinopathy.

Adult↗
PubMed2001

Atypical right atrial flutter patterns.

BACKGROUND: The purpose of our study was to define the incidence and mechanisms of atypical right atrial flutter. METHODS AND RESULTS: A total of 28 (8%) of 372 consecutive patients with atrial flutter (AFL) had 36 episodes of sustained atypical right AFL. Among 24 (67%) of 36 episodes of lower loop reentry (LLR), 13 (54%) of 24 episodes had early breakthrough at the lower lateral tricuspid annulus, whereas 11 (46%) of 24 episodes had early breakthrough at the high lateral tricuspid annulus, and 9 (38%) of 24 episodes showed multiple annular breaks. Bidirectional isthmus block resulted in elimination of LLR. A pattern of posterior breakthrough from the eustachian ridge to the septum was observed in 4 (14%) of 28 patients. Upper loop reentry was observed in 8 (22%) of 36 episodes and was defined as showing a clockwise orientation with early annular break and wave-front collision over the isthmus. Two patients had atypical right AFL around low voltage areas ("scars") in the posterolateral right atrium. CONCLUSIONS: Atypical right AFL is most commonly associated with an isthmus-dependent mechanism (ie, LLR or subeustachian isthmus breaks). Non-isthmus-dependent circuits include upper loop reentry or scar-related circuits.

Aged↗
PubMed2001

Interlocked feedback loops contribute to the robustness of the Neurospora circadian clock.

Interlocked feedback loops may represent a common feature among the regulatory systems controlling circadian rhythms. The Neurospora circadian feedback loops involve white collar-1 (wc-1), wc-2, and frequency (frq) genes. We show that WC-1 and WC-2 proteins activate the transcription of frq gene, whereas FRQ protein plays dual roles: repressing its own transcription, probably by interacting with the WC-1/WC-2 complex, and activating the expression of both WC proteins. Thus, they form two interlocked feedback loops: one negative and one positive. We establish the physiological significance of the interlocked positive feedback loops by showing that the levels of WC-1 and WC-2 determine the robustness and stability of the clock. Our data demonstrate that with WC-1 being the limiting factor in the WC-1/WC-2 complex, the greater the levels of WC-1 and WC-2, the higher the level of the FRQ oscillation and the more robust the overt rhythms. Our data also show that, despite considerable changes in the levels of WC-1, WC-2, and FRQ, the period of the clock has been limited to a small range, suggesting that the interlocked circadian feedback loops are also important for determining the circadian period length of the clock.

Circadian Rhythm↗
PubMed2001

Study on the abundance of CFCs varying with the latitude at the bottom of the troposphere in the southern hemisphere.

As the main ozone depleting compounds, the abundance of CFCs in the troposphere and stratosphere has been focused on all the while. However, there are few reports concerning on the CFCs' latitudinal dependence. Relying on the longterm monitoring that has been performed in Shanghai from 1997 and Cooperating with the Chinese Third Antarctic Inland Ice-sheet Traversal Party, we did intensive sampling in the southern hemisphere from the beginning of November to the end of December in 1998 and then got the corresponding concentrations of CFC-12, CFC-11, and CFC-113 according to the latitude. The data were studied inductively in accordance with the geographical location and meteorological condition of every sampling point. In summary, the average concentrations of CFCs (refer to CFC-11, CFC-12, and CFC-113) in equatorial area are the highest in the southern hemisphere; however, the concentrations in prevailing west-wind belt and polar east-wind belt are much lower and at the same levels, which should be a perfect implication of the mean background in the southern hemisphere. Being related to the special polar circumfluence, the concentrations of CFCs on the glacier reveal a special rise. Compared with the mean background of the southern hemisphere that is represented by the data of the prevailing west-wind belt and Polar east-wind belt, the concentrations in Shanghai bear the same level.

Air Movements↗
PubMed2001

Resuscitation of dormant Mycobacterium tuberculosis by phospholipids or specific peptides.

The presence of dormant tubercle bacilli presents a major problem for tuberculosis treatment. The culture supernatant of Mycobacterium tuberculosis was previously shown to resuscitate dormant bacilli in vitro. Here we report identification of active components as phospholipids and a tuberculosis protein Rv1174c. Remarkably, dormant bacilli from a one year old culture which failed to form any colonies could be resuscitated with peptides derived from Rv1174c and formed 10(5-7) colonies/ml. This finding represents the first unambiguous demonstration of resuscitation of dormant tubercle bacilli in vitro and may have implication for the study of mycobacterial dormancy and the design of novel strategies for improved treatment of tuberculosis.

Adaptation, Biological↗