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Biomedical subjects

L J Zhang

Publications and source records attributed to L J Zhang.

At least 37 records · Page 2Linked to original sources
PubMed2002

Emergence of multiple genotypes of H5N1 avian influenza viruses in Hong Kong SAR.

Although A/Hong Kong/156/97 (H5N1/97)-like viruses associated with the "bird flu" incident in Hong Kong SAR have not been detected since the slaughter of poultry in 1997, its putative precursors continue to persist in the region. One of these, Goose/Guangdong/1/96 (H5N1 Gs/Gd)-like viruses, reassorted with other avian viruses to generate multiple genotypes of H5N1 viruses that crossed to chickens and other terrestrial poultry from its reservoir in geese. Whereas none of these recent reassortants had acquired the gene constellation of H5N1/97, these events provide insight into how such a virus may have been generated. The recent H5N1 reassortants readily infect and kill chicken and quail after experimental infection, and some were associated with significant mortality of chickens within the poultry retail markets in Hong Kong. Some genotypes are lethal for mice after intra-nasal inoculation and spread to the brain. On this occasion, the early detection of H5N1 viruses in the retail, live poultry markets led to preemptive intervention before the occurrence of human disease, but these newly emerging, highly pathogenic H5N1 viruses provide cause for pandemic concern.

Animals↗
PubMed2002

H5N1 influenza viruses isolated from geese in Southeastern China: evidence for genetic reassortment and interspecies transmission to ducks.

The H5N1 viruses (H5N1/97) associated with the "bird-flu" incident in the Hong Kong SAR have not been isolated since the slaughter of poultry in December 1997 brought that outbreak to an end. Recent evidence points to this virus as having arisen through a reassortment of a number of precursor avian viruses and a virus related to Goose/Guangdong/1/96 (H5N1) (Gs/Gd/96) was the likely donor of the H5 hemagglutinin. We characterize the Goose/Guangdong/1/96-like viruses isolated from geese and ducks imported into Hong Kong in the year 2000. Antigenically and genetically, these recent H5N1 viruses fall into two groups, one mainly associated with geese, and the other, recently transmitted to ducks. Further, viruses isolated from a goose and a duck in December 2000 have acquired NS, PA, M, and PB2 genes from the aquatic avian influenza gene pool through reassortment. For pandemic preparedness, it is important to monitor whether these reassortant viruses have the capacity for interspecies transmission to terrestrial poultry or mammals.

Animals↗
PubMed2000

[Clinical analysis of 318 cases of new-mode cesarean section].

OBJECTIVES: To study types of new mode cesarean section (CS) and its clinical value. METHODS: Four hundred and sixty-eight pregnant women with operative indications were randomly divided into three groups: the new mode CS group whose peritoneum was not sewed, the new mode CS group whose peritoneum was sewed, and the lower segmental CS group. The duration of operation, bleeding volume, morbidity after operation, and B type ultrasound for examining the incision were observed. RESULTS: There were significant difference in the duration of operation, bleeding volume, and morbidity after operation between the lower segmental CS and the two types of the new mode CS (P < 0.05). There was no significant differences in the bleeding volume and morbidity after operation between the two types of the new mode CS (P > 0.05), but there were significant difference in the duration of operation and the incision examined by B type ultrasound (P < 0.05). CONCLUSION: The new mode CS has shorter operative period, less bleeding, weak pain, faster recovery of peristalsis, and lower incidence of post-operative morbidity.

Cesarean Section↗
PubMed2000

Effect of smoking on semen quality of infertile men in Shandong, China.

AIM: To study the effect of smoking on the semen quality in infertile men in Shandong Province, China. METHODS: Adult non-drinker males attending the infertility clinic, including 110 non-smokers and 191 smokers, were recruited for the study. Sixty-one fertile, non-smoker and non-drinker males, who had one or more children, served as the controls. The smokers were divided into subgroups according to the amount and duration of smoking. Semen parameters (semen volume and sperm density, viability, motility, and morphology) were examined and seminal plasma contents of Zn , Cu and superoxide dismutase (SOD) determined. RESULTS: The semen volume and acidity, and the sperm density, viability and forward progression, as well as the seminal plasma contents of Zn, Cu and SOD were much lower in the medium, heavy and long-term smokers than in the non-smokers (P < 0.01). The sperm density, viability and forward progression, and the seminal plasma Zn, Cu and SOD levels were negatively correlated with the amount and duration of cigarette smoking (P < 0.01). CONCLUSION: Medium, heavy and long-term smoking adversely affected the semen quality in a population of men visiting the infertility clinic in Shandong, China.

Adult↗
PubMed1999

The components of an inorganic physiological buffer for Penaeus chinensis.

Shrimp Penaeus chinensis, 5--8 cm in body-length were held in laboratory aquaria after collection from culture ponds at Laoshan in Qingdao in 1992. The osmotic pressure and the concentration of inorganic components of hemolymph in the shrimp were measured. The optimum pH and osmolarity of the buffer were determined from tests on primary cultures of hepatopancreatocytes in vitro. The results indicate that the hemolymph is homoiosmotic to 27 ppt seawater at 870 mOsm/L; osmotic regulation of shrimp is strong in low-salinity seawater, but weak in high-salinity seawater; the concentration of Mg(2+) ions in hemolymph is much less than that in seawater, while [K(+)] and [Ca(2+)] are much higher; hepatopancreatocytes in vitro have optimal survival at osmolarity range of 780-1, 100 mOsm/L and pH 6.5. Accordingly, an inorganic physiological buffer for P. chinensis (PPB, Penaeid Physiological Buffer) was prepared and contains NaCl, 23.0 g/L; K(2)SO(4), 1.1 g/L; CaCl(2), 1.6 g/L; MgSO(4).7H(2)O, 1.6 g/L; NaH(2)PO(4).2H(2)O, 0.35 g/L; NaHCO(3), 0. 05 g/L; pH 6.5; osmolarity, 867.9 mOsm/L. For storage of PPB, 4 stock buffers are made: 1) 10x PPB-A, which contains 230 g/L NaCl, 11 g/L K(2)SO(4), and 3.5 g/L NaH(2)PO(4).2H(2)O; 2) 40x PPB-B, which contains 64 g/L MgSO(4).7H(2)O; 3) 40x PPB-C, which contains 64 g/L CaCl(2); and 4) 100x PPB-D, which contains 50 g/L NaHCO(2). In order to increase the buffering capacity, PPB may be modified (to His-PPB), in which 5 g/L Histidine.HCl is used as the buffer reagent in place of NaH(2)PO(4) and NaHCO(3).

Animals↗
PubMed1997

The interleukin-2 fusion protein, DAB389IL-2, inhibits the development of infectious virus in human immunodeficiency virus type 1-infected human peripheral blood mononuclear cells.

DAB389IL-2 is a genetically engineered fusion protein that reduces human immunodeficiency virus type 1 (HIV-1) replication in activated, interleukin (IL)-2 receptor (IL-2R)-expressing human peripheral blood mononuclear cells (PBMC). The level of infectious virus released by cultured PBMC after treatment with DAB389IL-2 was measured by a quantitative microculture assay. The inhibition of p24 antigen production was also evaluated in cultures that differed in duration of infection and activation state. Although the activation state of the cell and the time of DAB389IL-2 addition to the cultures influenced its anti-HIV activity, DAB389IL-2 treatment decreased levels of infectious HIV-1 to 0.1%-6.5% of untreated cell levels. DAB389IL-2 also decreased p24 antigen expression to 10%-48% of controls, even when added as late as 8 days after acute infection. Mutational variants of DAB389IL-2 that lack catalytic activity or IL-2R binding are without anti-HIV activity.

Anti-HIV Agents↗
PubMed1997

Cloning and characterization of Ras-GRF2, a novel guanine nucleotide exchange factor for Ras.

Conversion of Ras proteins into an activated GTP-bound state able to bind effector proteins is catalyzed by specific guanine nucleotide exchange factors in response to a large number of extracellular stimuli. Here we report the isolation of mouse cDNAs encoding Ras-GRF2, a multidomain 135-kDa protein containing a COOH-terminal Cdc25-related domain that stimulates release of GDP from Ras but not other GTPases in vitro. Ras-GRF2 bound specifically to immobilized Ras lacking bound nucleotides, suggesting stabilization of the nucleotide-free form of Ras as a mechanism of catalyzing nucleotide exchange. The NH2-terminal region of Ras-GRF2 is predicted to contain features common to various signaling proteins including two pleckstrin homology domains and a Dbl homology region. Ras-GRF2 also contains an IQ motif which was required for its apparent constitutive association with calmodulin in epithelial cells ectopically expressing Ras-GRF2. Transient expression of Ras-GRF2 in kidney epithelial cells stimulated GTP binding by Ras and potentiated calcium ionophore-induced activation of mitogen-activated protein kinase (ERK1) dependent upon the IQ motif. Calcium influx caused Ras-GRF2 subcellular localization to change from cytosolic to peripheral, suggesting a possible mechanism for controlling Ras-GRF2 interactions with Ras at the plasma membrane. Epithelial cells overexpressing Ras-GRF2 are morphologically transformed and grow in a disorganized manner with minimal intercellular contacts. Northern analysis indicated a 9-kb GRF2 transcript in brain and lung, where p135 Ras-GRF2 is known to be expressed, and RNAs of 12 kb and 2.2 kb were detected in several tissues. Thus, Ras-GRF2 proteins with different domain structures may be widely expressed and couple diverse extracellular signals to Ras activation.

Amino Acid Sequence↗
PubMed1997

[Study of different pattern of immuno-modulatory mechanism by tonifying kidney and invigorating spleen].

OBJECTIVE: To observe the acting pattern on the immune system by tonifying the Kidney (TK). METHODS: Three composite recipes were used on the 7- and 14-day corticosterone rat model to study the effect of recipes on the different pattern of immuno-modulatory and neuroendocrinological systems. RESULTS: The immune system of Invigorate the Spleen(IS) group was well protected in either 7-day or 14-day experiment, without any effect of IS recipe acting on the neuroendocrine system, it suggested that IS recipe might have direct action on immune system, while TK group with no effect on neuroendocrine-immune (NEI) system in 7-day experiment, but showed the remarkable protective effect of the whole NEI system until 14-day experiment. CONCLUSION: The results indicated that TK recipe is acting on the neuro endocime system first, and then influence the immune system. It means that the action was through down pathway of NEI network.

Animals↗
PubMed1995

Mutation-deletion analysis of a Ca(2+)-dependent phospholipid binding (CaLB) domain within p120 GAP, a GTPase-activating protein for p21 ras.

p120 GAP is a GTPase activating protein for p21 ras. It is a multidomain protein which exhibits sequence similarity with other GTPase-activating proteins, src, pleckstrin and a central portion of the protein kinase C conserved region 2 domain known as CaLB (Ca(2+)-dependent phospholipid-binding). The presence of this CaLB motif has led to the speculation that p120 GAP may be a member of a family of structurally related proteins containing a Ca(2+)-dependent membrane/lipid-binding domain. Here we have studied the in vitro Ca(2+)-dependent phospholipid-binding properties of the isolated proposed CaLB sequence in human GAP and deduce that a phospholipid-binding sequence is indeed located between amino acids 606 and 648. Binding of phosphatidylserine and phosphatidylinositol, but not phosphatidylcholine, within this sequence is Ca(2+)-dependent, with an estimated EC50 for Ca2+ of approx. 1 microM. Using deletion-mutation analysis we have further defined the minimal boundaries for this in vitro phospholipid-binding activity. p120 GAP amino acids 612-643 exhibit full phospholipid-binding activity, but further deletion of either amino acids 612-617 or amino acids 633-648 significantly decreased or abolished phospholipid binding. These studies establish that amino acids 612-643 of p120 GAP indeed constitute a functional CaLB domain and thereby imply a role for Ca2+ in the regulation of p120 GAP association with cellular (membrane) phospholipids.

Amino Acid Sequence↗
PubMed1995

CaLB: a 43 amino acid calcium-dependent membrane/phospholipid binding domain in p120 Ras GTPase-activating protein.

CaLB was originally observed as a conserved sequence motif in various calcium-responsive signalling proteins and also in p120 Ras GTPase activating protein (p120GAP) (Clark et al. Cell 65: 1043-1051, 1991). Here we show the 43 residue CaLB motif in p120GAP is a functional protein domain that when expressed as a fusion protein in vitro confers Ca(2+)-dependent interactions with cellular membranes and phosphatidylserine and phosphatidylinositol vesicles. p120GAP, but not a mutant lacking the CaLB domain, associates with the particulate fraction of cells in response to elevated intracellular Ca2+ suggesting that p120GAP may be regulated in part by calcium signals. Addition of the p120GAP CaLB domain was able to restore transforming activity and particulate localization to an otherwise transformation-defective and cytosolic mutant v-Sre tyrosine kinase. The CaLB domain appears to be a prevalent protein module that may affect the molecular interactions and subcellular localization of signalling proteins.

3T3 Cells↗
PubMed1995

Detection of human cytomegalovirus DNA, RNA, and antibody in normal donor blood.

Peripheral blood samples from 313 normal donors were tested for prior human cytomegalovirus (HCMV) infection: 37%, 0.9%, and 43% of the samples were positive by antibody detection, DNA hybridization, and RNA hybridization assays, respectively. An early mRNA, which is transcribed from a HindIII-b fragment of the CMV genome and detected with an antisense RNA probe, can be detected more frequently than antibody and CMV DNA. The early CMV mRNA transcripts can be detected in the peripheral white blood cells in 44% of HCMV-seronegative blood donors. Blood samples that were CMV RNA positive but antibody negative comprised 27% of the tested samples. Whether CMV RNA in donor blood indicates that CMV can be transmitted via blood transfusion must be determined by further studies.

Antibodies, Viral↗
PubMed1995

[Effect of ming-men mixture on corticosterone-rats' neuro-endocrino-immunological network].

The hypothalamus-pituitary adrenal-thymus(HPAT) axis is an important form of the neuroendocrino-immunological network (NEIN). To study the essential link between Ming-Men, Kidney and the NEIN, the corticosterone (CORT) injected rats was used. The CORT The CORT caused HPAT axis inhibiting model was established and then the regulation of Ming-Men mixture (MMM) was observed. The results showed that the number of corticotropin-releasing factor (CRF) positive neurones in hypothalamic paraventricular nucleus, CRF positive neurofibril in in median eminence, anterior pituitary ACTH positive secretory cells decreased markedly in the CORT inhibited rats and the immunohistochemical ABC staining became lighter than the control. We also observed that there was atrophy in adrenal, especially fasculate zone became thinner compared with the control. The thymus atrophied, the number of lymphocytes and thymic corpuscles decreased obviously. The content of ACTH and CORT in plasma decreased, the proliferative reaction of lymphocytes, interleukin-2 and the inductive ability of gamma-IFN reduced. After the MMM was instilled into stomach in experimental group, it was foiund that MMM could improve the inhibition on HPAT axis caused by CORT significantly, P < 0.01. It suggested that MMM possibly was an effective and ideal prescription which could regulate the HPAT axis.

Animals↗
PubMed1995

A natural vaccine candidate strain against cholera.

E1 Tor Vibrio cholerae (EVC) strains may be classified into two kinds-epidemigenic (EEVC) strains and non-epidemigenic (NEEVC) strains-based on a phage-biotyping system. A large number of EEVC strains have been screened for toxigenic and putative colonization attributes. One such naturally occurring strains (designated IEM101) has been found which is devoid of genes encoding cholera toxin (CT), accessory cholera enterotoxin (ACE), zonula occludens toxin (ZOT), but possesses RS1 sequences and toxin-coregulated pilus A gene (icpA) although icpA is poorly expressed. It expresses type B pili but does not possess type C pili. It is an E1 Tor Ogawa strain and does not cause fluid accumulation in rabbit ilcal loop tests. Active immunization of rabbits with strain IEM101 elicited good protection against challenge with virulent strains of V. cholerae O1. Oral administration caused no side effects in 15 human volunteers, colonized the gut for four to ten days and elicited good immune responses.

Animals↗
PubMed1995

[Effect of yougui yin on the content of monoaminic transmitters and body weight, food and fluid intake in corticosterone-rats].

Great attention has been paid to the relationship between the central monoaminic transmitters and the hypothalamus-pituitary-adrenal (HPA) axis recently. This paper reported the content of hypothalamic monoaminic transmitters of rats, which were injected with corticosterone 10 mg/kg subcutaneously for 14 days. The body weight as well as volume of food and fluid intake were measured in the same period. Effect of Yougui Yin (YGY, administrated by gastrogavage) on he cortico-inhibited rats was also observed. Results showed that the contents of hypothalamic monoaminic transmitters such as norepinephrine, Dopamine, 3,4-Dihydroxyphenylalanine, serotonin, and 5-hydroxyindole acetic acid of the rats increased obviously, while the body weight, volume of food and fluid intake decreased significantly day by day. The YGY could improve the above-mentioned indexes significantly. It suggested that: (1) The synthesis and metabolism of the central monoaminic transmitters of rats activated when the HPA axis was inhibited by exogenous glucocorticoid, their body weight lowered, and the volume of food and fluid intake decreased. (2) YGY could improve the inhibited HPA axis, and inhibit the activated central monoaminic transmitters as well as protect the normal regulating function of hypothalamus on food and fluid intake.

Animals↗
PubMed1994

Regulation by lithium of the antagonistic effect of cholecystokinin octapeptide on ohmefentanyl-induced antinociception.

The antagonistic effect on opioid analgesia of central cholecystokinin octapeptide (CCK-8) has been amply demonstrated by behavioral and electrophysiological studies, although the mechanisms of action remain obscure. Since the phosphatidylinositol (PI) system is known to be involved in CCK effects in pancreatic tissue, and lithium has been shown to interfere with PI turnover, we sought to investigate whether LiCl would block the antiopioid effect of CCK-8 in the CNS. Nociceptive thresholds were assessed by the latency of the tail flick response (TFL). Intrathecal injection (ith) of LiCl at 4 cumulative doses (1.25-25 mumol) produced no significant change in the baseline TFL, nor was the antinociceptive effect induced by ohmefentanyl (OMF, the mu-selective opioid agonist, 20 ng, ith) reversed by LiCl. However, OMF-induced antinociception was dose-dependently reversed by CCK-8 (1-16 ng, ith), which alone at 5 cumulative doses (1-20 ng) had no influence on TFL, and the reversal effect of CCK-8 could be readily antagonized by LiCl (0.6-20 mumol, ith). The results are interpreted to mean that the PI signal system may play an important role in mediating the antiopioid effect of CCK-8.

Analgesics↗
PubMed1994

[Multiload Cu250 intrauterine devices and VCu200 intrauterine devices for women with previous failure of stainless steel ring intrauterine devices: a 5-year randomized clinical trial].

Two hundred rural women with history of stainless steel ring (SSR) intrauterine devices (IUD) failure (i.e. expulsion or pregnancy with IUD-in-situ) were randomly allocated into Multiload Cu250 (MLCu250) or VCu200 group. The follow up rate was 97.5% at the end of 5-year. The 5-year gross cumulative continuation rates per 100 women for MLCu250 and VCu200 were 80.0 and 81.7 respectively. The 5-year cumulative expulsion rate was significantly lower in MLCu250 group (1.0) than that in VCu200 group (8.1) (P < 0.05), while the pregnancy rate was higher in MLCu group (12.0 vs. 4.1) but no statistical significant difference existed between the 2 groups. The removal for bleeding and (or) pain were similar (6.0 and 6.1). There was one ectopic pregnancy in each group and no removal for medical or personal reasons. The expulsion and pregnancy cases in the present study were not associated with their previous failures. It was concluded that both types of copper IUD were effective for women with previous failure of SSR. The study also showed that MLCu250 might be used as long as 5 years. Should surface area of copper be increased, further decreased pregnancy rate would be expected.

Adult↗
PubMed1994

The D2S and D2L dopamine receptor isoforms are differentially regulated in Chinese hamster ovary cells.

To investigate and compare the regulatory properties of the two isoforms of the D2 dopamine receptor, we have stably expressed their cDNAs in Chinese hamster ovary (CHO) cells. Cell lines were selected that express similar levels of [3H]methylspiperone-binding activity. Both isoforms mediate a dose-dependent and pharmacologically specific inhibition of adenylyl cyclase activity in both intact cell and membrane preparations. Pretreatment of both D2L and D2S receptor-expressing cells with 100 microM dopamine produces a approximately 5-fold shift (to lower affinity) in the EC50 for dopamine inhibition of cAMP accumulation, with a 25-30% decrease in the maximum response. Dopamine treatment also results in a approximately 25% decrease in the maximum receptor binding activity of the D2S receptor-expressing cells. In contrast, the D2L receptors are up-regulated by about 2-fold in response to dopamine exposure. This difference in response between the D2S and D2L receptors is not cell line specific, inasmuch as other CHO clones expressing these isoforms show identical responses. The dopamine-induced up-regulation of D2L receptor binding is time dependent, reaching maximal levels after 10 hr (t1/2 = 2 hr). Upon removal of dopamine, the receptor binding activity returns to control levels within 20 hr. The adenylyl cyclase desensitization response is also time dependent but exhibits a slower time course (t1/2 = 5 hr) than the receptor up-regulation. Both regulatory responses are induced in a dose-dependent fashion by dopamine, albeit with different potencies (up-regulation EC50 = 100 nM, desensitization EC50 = 2 microM). These regulatory effects are pharmacologically specific, being mimicked by D2-selective agonists but not agonists of other receptor subtypes. The dopamine-induced receptor up-regulation is blocked by prior treatment of the cells with pertussis toxin and is not mimicked by cAMP analogs. Conversely, elevation of intracellular cAMP levels results in down-regulation of the D2L receptor activity. To test whether protein synthesis is required for the D2L receptor up-regulation, cycloheximide was used to block mRNA translation. This was found to completely inhibit the up-regulation of D2L binding activity; however, there was no effect on the desensitization of the adenylyl cyclase response. RNA dot-blot analyses indicate that dopamine treatment is associated with a sustained 2-fold increase in the steady state levels of D2L mRNA, whereas D2S mRNA is transiently increased by only 50%.(ABSTRACT TRUNCATED AT 400 WORDS)

Adenylyl Cyclase Inhibitors↗