Biomedical subjects

G Cai

Publications and source records attributed to G Cai.

At least 73 records · Page 4Linked to original sources

PubMed1997

Natural history of Diagnostic Interview Schedule/DSM-IV major depression. The Baltimore Epidemiologic Catchment Area follow-up.

BACKGROUND: Natural history can be characterized by incidence, recurrence, and duration of episodes. Research on the incidence of major depression is rare; studies of recurrence and duration are limited to clinical samples. METHODS: The Baltimore, Md, site of the Epidemiologic Catchment Area Program followed up its 1981 baseline cohort of 3481 respondents with an additional assessment in 1993 to 1996. Interviews were obtained from 1920 respondents (73% of the survivors). The Diagnostic Interview Schedule and the same survey procedures as in 1981 were used, augmented with a Life Chart Interview for dating the onset and duration of syndromes. RESULTS: There were 71 new cases of Diagnostic interview Schedule/DSM-IV major depression and 23,698 person-years of exposure, generating an estimated incidence of 3.0 per 1000 per year. Incidence peaked while subjects were in their 30s, with a smaller peak when they were in their 50s. Prodromal symptoms often occurred many years before the full criteria for diagnosis were met. Women were at higher risk for becoming new cases but had neither higher risk for recurrence nor longer episodes than men. Episodes of depression lasted for 12 weeks. The duration of an episode, and time to an episode-free year, was longer in the first episode than in recurrent episodes. CONCLUSIONS: The incidence estimated in this study is consistent with that found in the few other similar studies performed. The bimodality of onset suggests the value of further exploring the heterogeneity of depression via its natural history. Reported differences in prevalence between men and women seem to be due to differences in incidence, not chronicity.

Adolescent↗

PubMed1997

Comparison of the effects of interleukin-1 alpha, interleukin-1 beta and interferon-gamma-inducing factor on the production of interferon-gamma by natural killer.

Interferon-gamma inducing factor (IGIF) is a recently identified cytokine which stimulates the production of interferon-gamma (IFN-gamma) by T cells and enhances natural killer (NK) cell cytolytic activity. Protein fold recognition, structure prediction and comparative modeling have revealed that IGIF is a member of the interleukin (IL)-1 cytokine family and has prompted the designation IL-1 gamma. Here we report functional similarities between members of the IL-1 family by comparing the effects of IL-1 alpha, IL-1 beta and IGIF on NK cell production of IFN-gamma. All three IL-1 types enhanced NK cell production of IFN-gamma when induced by IL-2 or IL-12, although at high concentrations (> 10 ng/ml), IGIF was five- to tenfold more potent than IL-1 alpha or IL-1 beta. This effect correlated with enhanced levels of mRNA for IFN-gamma when NK cells were stimulated with IGIF plus IL-12. In contrast to IL-12 and IL-2, the ability of IGIF to stimulate NK cell production of IFN-gamma was not increased by IL-1 alpha or IL-1 beta. The ability of IGIF to enhance IFN-gamma production was independent of the type I and type II IL-1 receptors or the IL-1R accessory protein. Together, these results identify IGIF as a potent stimulator of NK cell production of IFN-gamma and demonstrate that the effect of IGIF on NK cell production of IFN-gamma is similar to that of IL-1 alpha and IL-1 beta but distinct from that of IL-12.

Adjuvants, Immunologic↗

PubMed1997

Expression of matrix metalloproteinase-9 mRNA in osteoporotic bone tissues.

Matrix metalloproteinases (MMPs), a sort of important enzymes involved in extracellular matrix metabolism, play critical roles in the process of tissues remodeling, wound healing and metastasis of tumors. Dot blot and in situ hybridization were used in this study to detect the expression and localization of MMP-9, an important proteolytic enzyme implicated in bone resorption in bone tissues. The results showed that the level of MMP-9 mRNA expression in osteoporotic bone tissues was significantly higher than that in normal control group and the cell types that expressed MMP-9 mRNA included mono- and multi-nuclear osteoclasts and some lining cells on the surface of bone matrix. It was suggested that MMP-9 play a key role in the development of bone loss in osteoporosis.

Animals↗

PubMed1997

Functional interactions among cytoskeleton, membranes, and cell wall in the pollen tube of flowering plants.

The pollen tube is a cellular system that plays a fundamental role during the process of fertilization in higher plants. Because it is so important, the pollen tube has been subjected to intensive studies with the aim of understanding its biology. The pollen tube represents a fascinating model for studying interactions between the internal cytoskeletal machinery, the membrane system, and the cell wall. These compartments, often studied as independent units, show several molecular interactions and can influence the structure and organization of each other. The way the cell wall is constructed, the dynamics of the endomembrane system, and functions of the cytoskeleton suggest that these compartments are a molecular "continuum," which represents a link between the extracellular environment and the pollen tube cytoplasm. Several experimental approaches have been used to understand how these interactions may translate the pollen-pistil interactions into differential processes of pollen tube growth.

Cell Membrane↗

PubMed1997

Association analysis of the dopamine D4 gene exon III VNTR and heroin abuse in Chinese subjects.

Although social and cultural influences are clearly important, family, twin and adoption studies indicate that genes contribute significantly to substance abuse. Substance abuse is associated with novelty seeking, a heritable human personality trait which may be influenced by alleles of the dopamine D4 (DRD4) gene exon III VNTR. Consequently Kotler et al analysed the DRD4 VNTR in opiate-dependent subjects from Israel, and found a significant excess of the 7-repeat allele. We have attempted to replicate this finding using a Han Chinese case-control sample of 121 heroin-dependent subjects and 154 normal controls. We found two 7-repeat alleles which occurred exclusively in the patient group, and overall there was an excess of longer alleles, which did not reach significance (chi 2 = 7.04; P = 0.07). When the D4 VNTR was divided into 'long' (5-7 repeats) and 'short' (2-4 repeats), a significant excess of long alleles was observed in the patient group (P = 0.023, one-tailed), with an odds ratio of 2.30 (95% CI 1.07-4.93). We conclude that our findings support the hypothesis that alleles of the DRD4 exon III VNTR are susceptibility factors for heroin abuse.

Adolescent↗

PubMed1997

Catechol-O-methyltransferase Val158Met polymorphism: frequency analysis in Han Chinese subjects and allelic association of the low activity allele with bipolar affective disorder.

Catechol-O-methyltransferase catalyses the O-methylation of biologically active or toxic catechols and is a major component of the metabolism of drugs and neurotransmitters such as L-dopa, noradrenaline, adrenaline, and dopamine. Human catechol-O-methyltransferase activity is an autosomal partially dominant trait and is strongly associated with a valine to methionine substitution at codon 158 of the protein. About 25% of Caucasians have low activity, 50% intermediate activity and 25% high activity as determined by either phenotypic or genotypic measurement. In black populations, the low activity allele (Met158; COMTL) is less frequent with about 7% being homozygous. Using a PCR based genotyping assay, we report that the Met158 allele is also less frequent in normal Han Chinese subjects with about 3% of the population being homozygous. Because of its role in catecholamine metabolism and several lines of evidence pointing to a locus for psychosis near the COMT gene on chromosome 22q11, we have analysed the COMT Val158Met polymorphism as a candidate susceptibility factor for bipolar affective disorder. We report an association between bipolar affective disorder and the Met158 allele (p = 0.004) and genotype (p = 0.01) in 93 affected Chinese subjects and 98 controls. We hypothesize that either the low activity allele of catechol-O-methyltransferase is a risk factor for bipolar affective disorder in Chinese populations or is in linkage disequilibrium with a nearby susceptibility gene or polymorphism.

Bipolar Disorder↗

PubMed1997

[Detection of the level of serum antigen recognized by McAbGB2 in breast cancer].

This study sought to verify the levels of serum antigen recognized by McAbGB2 (abbr. serum McAbGB2 antigen) in patients with breast cancer. We adopted the ELISA method and used McAbGB2 to detect the level of serum McAbGB2 antigen in 50 normal persons and 60 patients with breast cancer. The results showed that the level of serum McAbGB2 antigen of 17 preoperative patients with breast cancer was significantly different from that of the normal persons (P < 0.001); the rate of agreement on positivity for the 17 preoperative patients with breast cancer was 88.2% (15/17); the levels of serum McAbGB2 antigen in 8 patients among the 17 preoperative patients with breast cancer decreased from 57.5 +/- 51.3 u/ml (preoperation) to 20.6 +/- 4.98 u/ml (postoperation; the levels of serum McAbGB2 antigen in the other 43 operated patients with breast cancer almost remained normal during post-operative chemotherapy. These suggest that serum McAbGB2 antigen is a marker for breast cancer and can be used for serological diagnosis, treatment and prognosis inspection.

Antibodies, Monoclonal↗

PubMed1997

[Observation of the serum acidic isoferritin levels in patients with hepatocellular carcinoma].

The levels of serum acidic isoferritin (SAIF) in 48 patients with hepatocellular carcinoma (HCC), 30 patients with hepatitis, 28 patients with liver cirrihosis, and 33 healthy subjects were measured by using enzyme-linked immunosorbent assay (ELISA--double-determinant). The result revealed that the SAIF values of HCC, HP and LC did not show normal distribution. The median values were 440 micrograms/L, 21 micrograms/L, 120 micrograms/L and, in normal subjects, 66 micrograms/L respectively. There were statistically significant differences between HCC and the control groups. The sensitivity of SAIF to HCC was 85.46%, with the cut-off point being 250 micrograms/L. SAIF was not correlated to AFP in HCC cases. The values of SAIF had no relationship with the volume of the tumors and the clinical stages. SAIF may be an available and useful serum marker and be beneficial to the diagnosis of early-staged HCC.

Adolescent↗

PubMed1997

[Primary study on the use of ovariectomized rabbits for establishment of osteoporosis model].

Purebred New Zealand female rabbits were used in this study for demonstrating the feasibility of establishing rabbit's primary osteoporosis model. Bilateral ovariectomies were performed. Five to eight months after operation, we observed the BMD, weight, hair colour and living condition of the model. After killing the rabbits, we made biomechanical detection and pathologic histomorphometry using the bones. The weight of bone ash, the content of calcium and phosphorus, and the weight of metra were determined. The results showed that BMD, bone bending stress, weight of bone ash, content of calcium and phosphorus in ash, and weight of metra all decreased (P < 0.05); the number of trabecula decreased and the bone cortex became thinner. All these parameters evidenced the primary founding of rabbit's osteoporosis model. This research provides a basis for studying the pathogenesis of primary osteoporosis and evaluating the efficacy of pharmacotherapy.

Animals↗

PubMed1997

[Anti-virus effect of hepatocyte stimulating substance (HSS) on duck hepatitis B virus in vivo].

We used one day old Beijing ducklings infected by duck hepatitis B virus as experimental model to observe anti-virus effect of HSS. Beijing ducklings hatched within one day were injected intravenously with duck hepatitis B virus (DHBV). Positive DHBV-DNA in ducklings' sera were detected 7 days later. Serum samples were obtained from all ducklings before, during and after drug treatment at different times and stored at -70 degrees C. The collected samples were detected DHBV-DNA by dot-blot hybridization test at the same time. The therapeutic effects were evaluated by OD value of dot-blot and by the inhibitory rate of DHBV-DNA. The results showed that HSS (with 50 mg/kg/day and 200 mg/kg/day) were effective in inhibition of DHBV-DNA during and after drug treatment, especially in the HSS group of large dosage. The inhibitory effect appeared early and high dynamic. The inhibitory rate of DHBV-DNA during and after drug treatment were higher than the NS group (P < 0.05). No inhibitory effect was observed in NS group. The hepatic biopsy showed HSS groups had milder damage than NS group, indicating that the HSS could inhibit the replication of DHBV-DNA in Beijing ducklings.

Animals↗

PubMed1997

[Determination of dimethyl ether correction factors in gas chromatography with TCD and FID].

Dimethyl ether (DME) correction factors in gas chromatography with thermal conductivity detector (TCD) and flame ionization detector (FID) by using H2 as carrier gas were determined in this work. The homemade DME gas was quantitatively absorbed in ice-cold water. With ethanol as standard, the aqueous mixture was injected into a gas chromatograph, equipped with serially-connected TCD and FID. The weight correction factors of DME based on methanol were 0.86 and 0.55 for TCD and FID respectively. The result for TCD was also confirmed by calculation based on the stoichiometrical transformation of methanol into DME in reaction gas chromatography.

English Abstract↗

PubMed1997

Heterologous desensitization of the rat tail artery contraction and inositol phosphate accumulation after in vitro exposure to phenylephrine is mediated by decreased levels of Galphaq and Galphai.

Desensitization of alpha-1 adrenoceptor (alpha1AR)-mediated responses in aortic smooth muscle after exposure to catecholamines or alpha1AR agonists has been widely demonstrated. To determine whether exposure to an alpha1AR agonist results in desensitization of alpha1AR-mediated responses in a resistance artery, rat tail artery rings were exposed to 7.5 or 75 microM phenylephrine (PE) for 22 hr in vitro. Norepinephrine-stimulated contraction was significantly reduced in PE-exposed tail artery rings. Contractions mediated by the alpha2AR agonists, clonidine and UK 14,304, and by serotonin were also reduced in PE-treated tail artery rings. However, the contractile responses to KCl and ionomycin remained unchanged. Norepinephrine-, PE-, endothelin- and serotonin-stimulated inositol phosphate accumulations were reduced in PE-exposed tail artery rings, whereas KCl- and ionomycin-stimulated inositol phosphate accumulation remained unchanged. The density of membrane alpha1ARs, measured by specific [125I]2-([beta-(4-hydroxyphenyl)ethyl]aminomethyl)-1-etralone binding was not changed in PE-desensitized tail arteries. Further studies were performed to examine if alterations in receptor/G protein interaction accompanies arterial desensitization. In these studies receptor-stimulated increases in [35S]GTPgammaS binding to G proteins was assessed in membranes obtained from vehicle (control) and PE-treated tail arteries. In control membranes alpha1AR stimulation increased [35S]GTPgammaS binding to Galphaq and Galphai proteins, whereas the alpha2AR agonist UK14,304 activated [35S]GTPgammaS binding to Galphai exclusively. Both PE- and UK14, 304-induced responses were reduced in membranes from tail arteries that were exposed to either 7.5 or 75 microM PE for 22 hr. Western blot analyses of G protein alpha and beta subunits demonstrated that Galphaq and Galphai protein levels were decreased in PE-exposed tail artery membranes. These data show that the reduced transmembrane signaling for the alpha1AR in tail artery after in vitro PE exposure is associated with decreases in Galphaq and Galphai protein levels. The reduction in these Galpha proteins also appears to mediate the loss of function of alpha2AR and perhaps of other G protein-coupled receptors.

Adrenergic alpha-Agonists↗

PubMed1997

Reduced adenosine A1 receptor and G alpha protein coupling in rat ventricular myocardium during aging.

Adenosine A1 receptor (A1-AdoR) function in rat ventricles has previously been shown to decrease with age. In the present study, using the ligand [3H]8-cyclopentyl-1,3-dipropylxanthine ([3H]DPCPX) and coimmunoprecipitation of A1-AdoRs with their associated G proteins, we determined the specific binding of A1-AdoR and A1-AdoR/G protein coupling in ventricular myocardium of 6- to 24-month-old Fischer 344 rats. The densities (Bmax) of A1-AdoRs were 5.8 +/- 0.8 fmol/mg protein in 6-month-old rats and 6.1 +/- 1.4 fmol/mg protein in 24-month-old rats, and the dissociation constants (Kd) were 0.32 +/- 0.04 nmol/L in 6-month-old rats and 0.34 +/- 0.05 nmol/L in 24-month-old rats (P > .05). Analysis of the dose-dependent displacement of [3H]DPCPX binding by the selective A1-receptor agonist, N6-p-sulfophenyladenosine (SPA), yielded two affinity binding sites in both 6- and 24-month-old rats. However, the proportion of high-affinity A1-AdoRs was significantly lower in 24-month-old rats (23.5%) compared with 6-month-old rats (54.9%) (P < .05). In solubilized ventricular membranes, specific [3H]DPCPX binding sites were detected in immunoprecipitates of G alpha i3 and G alpha o antisera but not with antibodies for other G alpha proteins. The basal coimmunoprecipitation of A1-AdoR with G alpha i3 and G alpha o proteins decreased by 22% and 21%, respectively, in ventricular membranes of 24-month-old rats compared with that in 6-month-old animals. A1-AdoR stimulation with SPA increased the coprecipitation of A1-AdoR with G alpha i3 and G alpha o proteins by 287% and 245%, respectively, in 6-month-old rats but only by 129% and 140%, respectively, in 24-month-old rats (P < .01). In the absence of changes in A1-AdoR density and G alpha protein levels, an age-related decline in high-affinity A1-AdoR binding sites and a reduction in the association of A1-AdoR with G alpha proteins suggest that the age-related decrease in ventricular A1-AdoR-mediated response is related to a reduction in the coupling between A1-AdoR and their G proteins.

Adenylyl Cyclase Inhibitors↗

PubMed1996

Purification of apolipoprotein H by polyethylene glycol precipitation.

A new method of polyethylene glycol precipitation followed by heparin affinity chromatography was established to purify apolioprotein H (Apo H, beta 2-glycoprotein I). This method is simple and effective and yields more harvest of Apo H (3-4 mg Apo H from 100 ml fetal bovine serum) than the current HClO4 extraction method. There are notable differences between Apo H purified by the polyethylene glycol method [Apo H (PEG)] and Apo H purified by the HClO4 method [Apo H (HClO4)] in respects of their SDS electrophoresis characteristics, circular dichroism spectroscopy, and isoelectric focusing graph. It is concluded that the strong acid HClO4 treatment may induce some disordered structure in Apo H molecule resulting in the lowering of molecular weight and pIs. Apo H (PEG) retains more integrated structure which may be related to its bioactivity.

Apolipoproteins↗

PubMed1996

Cardiovascular hypertrophy and increased vascular contractile responsiveness following repeated cocaine administration in rabbits.

The effects of repeated cocaine administration on contractile responses were studied in adult rabbits. Repeated cocaine exposure caused a significant increase in the maximal response of the aorta to the agonists norepinephrine and serotonin as well as the receptor- independent stimulus KCl when compared to the saline controls. Cocaine exposure caused a significant increase in the wet weights of both heart and aorta. When the contraction was normalized to the wet weight of the aorta there was no difference between rabbits administered cocaine and saline. Acute cocaine administration caused a time-dependent increase in immunoreactivity of the proto-oncogene c-Fos in the aorta. These results show that repeated cocaine administration leads to the development of cardiovascular hypertrophy.

Animals↗

PubMed1996

Identification of novel missense mutations (Phe310Leu and Gly439Arg) in a neonatal case of hypophosphatasia.

Hypophosphatasia is associated with a defect of the tissue-non-specific alkaline phosphatase gene. We performed a mutational analysis in a surviving patient diagnosed at birth as having hypophosphatasia, on the basis of a low level of serum alkaline phosphatase (ALP) activity and characteristic radiographical findings. She had two sisters, one of whom died of respiratory failure complicated by perinatal hypophosphatasia; the other seemed healthy, with a relatively low activity level of ALP. The patient's parents also had low ALP activity. Sequence analysis of the tissue-nonspecific alkaline phosphatase gene was performed, using genomic DNA and total RNA from the skin fibroblasts of the patient and the peripheral mononuclear cells of her parents. The conversion of Phe to Leu at codon 310 (F310L) and Gly to Arg at 439 (G439R) were identified in the patient. Interestingly, the reconstructive experiments demonstrated that the F310L mutant exhibited an ALP activity level 65% of the normal level, whereas the mutant G439R had no activity. Moreover, the digestion by StuI, after a PCR using complementary DNA extracted from fibroblasts of the patient and lymphocytes of her father, revealed a relatively low messenger RNA level of F310L. These findings suggest that the neonatal case of hypophosphatasia was associated with compound mutations, one of which caused the loss of ALP activity and the other of which caused a slight reduction of the ALP activity, with a relatively low level of messenger RNA.

Adult↗

PubMed1996

[Long-term follow-up results of eleven cases after resection of hepatic metastases from colorectal cancer].

Eleven patients with hepatic metastases from colorectal cancer survived more than 5 years after the resection were reviewed. There were 3 (27.3%) disease-free survivors, the longest survival period was 7 years and 2 months. Compared with 41 survivors of less than 5-year duration after resection, it was shown that close follow-up after resection of the primary cancer, detecting early subclinical hepatic metastases, preoperative lower level of CEA, tumor less or equal to 5 cm in size, single metastatic nodule and radical resection were important factors influening long-term survival (P < 0.05). It is of the opinion that early diagnosis, early resection and re-resection after detecting subclinical local recurrence and metastases play important role in improving long-term response.

Adult↗

PubMed1996

[Preparation and identification of monoclonal antibody GB2 directed against human breast cancer serum antigen].

Spleen cells from BALB/c mice immunized with human breast cancer serum antigen were fused with murine myeloma SP 2/0 cells. After screening with ELISA and limited-dilution cloning, one hybridoma which could stably secrete specific antibody was obtained and designated McAbGB2. The titer of McAbGB2 was up to 1.2 x 10(6) after purified by ammonium sulfate and DEAE-cellulose. The McAbGB2 was defined as murine IgG1 by agarose double immunodiffusiong. Immunoblotting analysis revealed that the antigens with molecular weights of 116 kd and 45 kd recognized by McAbGB2 were distributed in human breast cancer tissue and serum.

Animals↗