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Biomedical subjects

J Cao

Publications and source records attributed to J Cao.

At least 253 records · Page 14Linked to original sources
PubMed1996

Identification of RII-binding proteins in the mollusc Mytilus galloprovincialis.

Several proteins with M(r) > 70 kDa from various tissues of the sea mussel Mytilus galloprovincialis were specifically recognized in vitro by the regulatory subunit (type RII alpha) of cAMP-dependent protein kinase (cAPK) from porcine heart. However, none of these proteins interacted with the regulatory subunit of cAPK from the mollusc itself. The results suggest that, unlike mammalian RII, regulatory subunit from mussel lacks the specific residues responsible for interaction with R-binding proteins. Consequently, the identified molluscan RII alpha-binding proteins should play a distinct role from cAPK anchoring.

Animals↗
PubMed1996

Over-expression of HSP-70 protects astrocytes from combined oxygen-glucose deprivation.

Pretreatment by a sublethal insult is associated with induction of stress proteins and with protection from subsequent injury. Heat pretreatment protects the brain from subsequent ischemia, and is shown here to protect primary astrocyte cultures from subsequent oxygen-glucose deprivation. To determine whether the expression of a single stress protein, HSP-70, could account for much of this protection, we expressed HSP-70 or beta-galactosidase in astrocytes using retroviral vectors. Only 12% of astrocytes expressing HSP-70 died after 7 hours of oxygen-glucose deprivation compared to 65% of astrocytes expressing beta-galactosidase and 82% of normal astrocytes. Our data provide direct evidence that selective expression of HSP-70 enhances the survival of astrocytes challenged with heat or oxygen-glucose deprivation.

Animals↗
PubMed1996

Human T-cell lymphotropic virus type-I infection in the severe combined immunodeficiency mouse.

Human T-cell lymphotropic virus type-I (HTLV-I) is the etiologic agent of HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP) and adult T-cell leukemia (ATL). HAM/TSP and ATL occur infrequently among HTLV-I-infected individuals, and rarely develop in the same individual. To study host and viral factors involved in the induction, tissue tropism, as well as pathogenesis of HAM/TSP, peripheral blood lymphocytes (PBL) from 14 patients with HAM/TSP and from 9 controls were introduced into severe combined immunodeficiency (SCID) mice by intraperitoneal injection. Mice were followed for up to 26 weeks. Human IgG was produced from 2 to 14 weeks after reconstitution in all animals. Thirty-two of 44 mice (72%) showed circulating human antibody against the major viral protein products of HTLV-I. Analysis of viral sequences by polymerase chain reaction (PCR) demonstrated HTLV-I sequences in 21/38 (55%) brains and in 7/17 (41%) spinal cords from HTLV-I-hu SCID mice. No animal had clinical evidence of neurological impairment or pathological findings similar to those seen in HAM/TSP. Seven mice who received PBL from Epstein Barr virus (EBV)-seropositive patients developed an intraperitoneal lymphoma. In 2 mice an infiltration of brain by a lymphoblastic tumor of B/T cell type was observed. By PCR, all the tumors were EBV-positive; HTLV-I sequences were detected in 5 of them. Our study suggests that the HTLV-I-hu-SCID mouse provides a potentially valuable system for studying the production, kinetics, and pathogenicity of anti-HTLV-I antibody, and may help clarify the interaction of EBV and retroviruses in the development of disease.

Adult↗
PubMed1996

Chemopreventive effects of green and black tea on pulmonary and hepatic carcinogenesis.

The chemopreventive effects of decaffeinated green and black tea treatment on liver and lung tumorigenesis were examined in carcinogen-treated mice. Male C3H mice were given decaffeinated green or decaffeinated black tea in their drinking water prior to, during, and after treatment with diethylnitrosamine (50 micrograms/kg bw, i.p., once per week for 8 weeks). After 40 weeks of tea treatment, mice were sampled and examined for pulmonary and hepatic tumors. Mice treated with both DENA and tea displayed a significant decrease in the mean number of lung and liver tumors compared to DENA-only treated animals. Mice that received 0.63 or 1.25% green tea or 1.25% black tea exhibited a reduction in liver tumor numbers of 54, 50, and 63%, respectively from that seen in the DENA-only treated mice. Tea treatment also significantly decreased the multiplicity of lung adenomas. Mice receiving DENA and either 0.63 or 1.25% green tea or 1.25% black tea showed a decrease in the mean number of lung tumors of 40, 46, and 34%, respectively, from DENA-only treated mice. While a possible association between the chemopreventive activity of tea on lung tumor response and the concentration of (-) epigallocatechin gallate (EGCG) in the tea was suggested, no apparent relationship between EGCG concentration and liver tumor response was seen, however. These results show a dose-dependent chemoprevention of both lung and liver tumors by both black and green tea in diethylnitrosamine-treated C3H mice.

Adenoma↗
PubMed1996

Multivariate discriminant analysis of the electromyographic interference pattern: statistical approach to discrimination among controls, myopathies and neuropathies.

The stepwise linear discriminant analysis method is used to develop optimal combinations of features measured from the electromyographic interference pattern, with the aim of minimising the misclassification rate in controls while maximising the correct classification rates in patients with disease. This discriminant analysis among multiple groups leads to the determination of the optimal discriminating surface in a multivariable space and can also produce a severity of disease likelihood index. Applying these combinations of features to 186 studies performed in the biceps muscle, 81% of all studies are accurately classified as being normal, myopathic or neuropathic. An algorithm to perform this stepwise multigroup linear discriminant analysis is described.

Diagnosis, Differential↗
PubMed1996

Dibutyl phthalate purged autologous bone marrow transplant in the treatment of leukemia.

It has been proved that di-N-butyl phthalate (DBP) is singular in killing leukemic cells selectively or accelerating the deterioration of residual leukemic cells in long-term marrow culture in vitro. Based on this principle, the DBP-purged autologous bone marrow transplant has been applied to the treatment of a group of 14 patients suffering from acute nonlymphocytic leukemia. After 5-10 days of in vitro co-culture of marrow cells with DBP at a concentration of 50 micrograms/ml, the recovery of total nucleated cells and the amount of CFU-GM were 67.5% and 68.1%, respectively. In all patients, the reconstitution of hematopoiesis was observed after pre-conditioning and transfusion of purged marrow cells. Among these, two patients had a relapse, two patients died from complications of transplant, one patient died from non-leukemic disease, and the others are all alive and free of disease; the mean survival time as calculated recently was 15 months. These preliminary clinical data support that marrow culture in the presence of DBP is a safe and effective measure for treating leukemia in purged autologous bone marrow transplant.

Adolescent↗
PubMed1996

Fluorine intake of a Tibetan population.

Measurements of food consumption of randomly selected families and fluorine levels in food and beverages were used to calculate the fluorine intake of Tibetan people living in nomadic or semi-nomadic areas of the region and regularly consuming brick tea both as a beverage and in food. The fluorine intake of these groups (children 5.49-7.62 mg day; adults 10.43-14.48 mg/day) was much higher than that of members of a Han population living in the region (children 1.44 mg/day; adults 2.54 mg/day). The amounts of fluorine consumed by the Tibetan inhabitants are at least twice the WHO suggested limit (2 mg/day). Tea plants are rich in fluorine, and the highest levels are found in older leaves which are used to make brick tea. We conclude that brick tea is the major source of fluorine intake by the Tibetan population studied.

Adolescent↗
PubMed1996

Apoptosis in renal cell carcinoma: detection by in situ end-labeling of fragmented DNA and correlation with other prognostic factors.

Because stage and grade of renal cell carcinoma (RCC) sometimes fail to predict the patient's outcome, additional prognostic predictors are needed. Apoptosis is a process of programmed cell death seen in both normal and neoplastic tissues, which has been shown to have prognostic significance in some tumor types. Forty-seven RCCs were studied for size, grade, stage, apoptosis, and proliferation. Fragmented DNA, a hallmark of apoptosis, was detected in situ by a process in which the fragmented DNA was labeled with a biotinylated nucleotide, which, in turn, was detected by an avidin-biotin-peroxidase labeling system. The proliferating tumor cells were detected by immunostaining with the MIB-1 antibody. The apoptotic index and proliferation index of each RCC were expressed as the number of tumor cells undergoing apoptosis and proliferation per 1,000 tumor cells. For grade I to IV RCCs, the median proliferative index was 13, 41, 119, and 143; the median apoptotic index was 8, 12, 39, and 73. For stage I to IV RCCs, the median proliferative index was 21, 34, 70, and 144; the median apoptotic index was 8, 9, 20, and 69. There was a statistically significant correlation of tumor grade, stage, and size with both proliferative index and apoptotic index. There was a statistically significant correlation between proliferation index and apoptotic index. In conclusion, apoptosis can be easily and reliably recognized by the in situ end labeling of fragmented DNA and may help predict the outcome of RCC.

Antibodies, Monoclonal↗
PubMed1996

Identification of major and minor chaperone proteins involved in the export of 987P fimbriae.

The 987P fimbriae of Escherichia coli consist mainly of the major subunit, FasA, and two minor subunits, FasF and FasG. In addition to the previously characterized outer membrane or usher protein FasD, the FasB, FasC, and FasE proteins are required for fimbriation. To better understand the roles of these minor proteins, their genes were sequenced and the predicted polypeptides were shown to be most similar to periplasmic chaperone proteins of fimbrial systems. Western blot (immunoblot) analysis and immunoprecipitation of various fas mutants with specific antibody probes identified both the subcellular localizations and associations of these minor components. FasB was shown to be a periplasmic chaperone for the major fimbrial subunit, FasA. A novel periplasmic chaperone, FasC, which stabilizes and specifically interacts with the adhesin, FasG, was identified. FasE, a chaperone-like protein, is also located in the periplasm and is required for optimal export of FasG and possibly other subunits. The use of different chaperone proteins for various 987P subunits is a novel observation for fimbrial biogenesis in bacteria. Whether other fimbrial systems use a similar tactic remains to be discovered.

Adhesins, Escherichia coli↗
PubMed1996

Molecular determinants of acute single-cell lysis by human immunodeficiency virus type 1.

Human immunodeficiency virus type 1 (HIV-1) infection of CD4-positive lymphocytes is accompanied by acute cytopathic effects, i.e., syncytium formation and single-cell lysis. Syncytium formation involves cell-cell fusion mediated by viral envelope glycoproteins on the surface of infected cells and by CD4 glycoproteins on adjacent cells. The molecular basis for the lysis of single-HIV-1 infected cells is unclear. Here we report that the expression of functional envelope glycoproteins from primary and laboratory-adapted HIV-1 isolates resulted in the lysis of single CD4-positive lymphocytes. As was previously observed in HIV-1 infected cultures, single-cell lysis in this system primarily involved necrosis and was not inhibited by soluble CD4. Binding of the viral envelope glycoproteins to the CD4 glycoprotein facilitated, but was not sufficient for, cytolysis. Importantly, the ability of the HIV-1 envelope glycoproteins to mediate membrane fusion was essential for single-cell killing. By contrast, the long cytoplasmic tail of the gp41 transmembrane envelope glycoprotein was neither necessary nor sufficient for single-cell lysis. These results suggest that intracellular envelope glycoprotein-CD4 interactions initiate autofusion events that disrupt cell membrane integrity, leading to single-cell lysis by HIV-1.

CD4-Positive T-Lymphocytes↗
PubMed1996

Effect of human immunodeficiency virus type 1 protein R (vpr) gene expression on basic cellular function of fission yeast Schizosaccharomyces pombe.

The human immunodeficiency virus type 1 (HIV-1) Vpr protein affects cell morphology and prevents proliferation of human cells by induction of cell cycle G2 arrest. In this study, we used the fission yeast Schizosaccharomyces pombe as a model system to investigate the cellular effects of HIV-1 vpr gene expression. The vpr gene was cloned into an inducible fission yeast gene expression vector and expressed in wild-type S. pombe cells, and using these cells, we were able to demonstrate the specific Vpr-induced effects by induction and suppression of vpr gene expression. Induction of HIV-1 vpr gene expression affected S. pombe at the colonial, cellular, and molecular levels. Specifically, Vpr induced small-colony formation, polymorphic cells, growth delay, and cell cycle G2 arrest. Additionally, Vpr-induced G2 arrest appeared to be independent of cell size and morphological changes. The cell cycle G2 arrest correlated with increased phosphorylation of p34cdc2, suggesting negative regulation of mitosis by HIV-1 Vpr. Treatment of Vpr-induced cell with a protein phosphatase inhibitor, okadaic acid, transiently suppressed cell cycle arrest and morphological changes. This observation implicates possible involvement of protein phosphatase(s) in the effects of Vpr. Together, these data showed that the HIV-1 Vpr-induced cellular changes in S. pombe are similar to those observed in human cells. Therefore, the S. pombe system is suited for further investigation of the HIV-1 vpr gene functions.

CDC2 Protein Kinase↗
PubMed1996

Inhibition of nascent-peptide release at translation termination.

The transcript leader of the human cytomegalovirus (CMV) gpUL4 (gp48) gene contains a 22-codon upstream open reading frame (uORF2) that represses translation of the downstream cistron. Previous work demonstrated that ribosomes stall at the termination codon of uORF2 and, remarkably, that the coding information of uORF2 is required for both the translational repression and ribosomal stalling. We now provide evidence that the peptide product of uORF2 is synthesized and is retained in the ribosome in the form of a peptidyl-tRNA. Translation of the gp48 transcript leader in cell extracts produces the 2.4-kDa uORF2 peptide and a second product migrating with an apparent molecular mass of 20 kDa that represents the uORF2 peptide covalently linked to tRNA(Pro), the tRNA predicted to decode the carboxy-terminal codon of uORF2. The uORF2 peptidyl-tRNA is only detected after translation of RNAs containing uORF2 sequences that also inhibit downstream translation and cause ribosomal stalling. These data support a model in which the nascent uORF2 peptide blocks translation termination prior to hydrolysis of the peptidyl-tRNA bond. This blockade results in ribosomal stalling on the transcript leader which in turn impedes the access of ribosomes to the downstream cistron. This system illustrates that translation termination may be a critical step controlling expression of some eukaryotic genes.

Cytomegalovirus↗
PubMed1996

Coding sequence-dependent ribosomal arrest at termination of translation.

A remarkably high percentage of proto-oncogene, growth factor, cellular receptor, and viral transcript leaders contain short upstream open reading frames (uORFs), yet the significance and regulatory effects of these uORFs have not been well characterized. In the case of the human cytomegalovirus gpUL4 (gp48) transcript, the second of three uORFs (uORF2) inhibits translation of the downstream cistron by a process that depends on the uORF2 amino acid coding information. To investigate the mechanism underlying this unusual regulatory element, we adapted the toeprinting (or reverse transcriptase extension inhibition) assay for use in detecting positions of ribosomal stalling on gp48 transcripts. Using a cell-free translation system, we demonstrate that ribosomes arrest at the termination codon of uORF2 by a uORF2 coding sequence-dependent mechanism. Further, the sequence requirements for ribosomal stalling are the same as for inhibition of downstream translation. We also provide evidence for ribosomal stalling in vivo, on the natural viral mRNA. These data support the hypothesis that the inhibition of downstream translation results from uORF2 peptide-dependent ribosomal arrest at termination and suggest that translation termination may be a regulatory step in expression of some eukaryotic genes.

Animals↗
PubMed1996

The relationship of fluorosis and brick tea drinking in Chinese Tibetans.

Brick tea-drinking fluorosis is an unusual environmental problem. As a result of an investigation of tea-drinking habits, total fluoride intakes, dental fluorosis, and skeletal fluorosis, this disease has been found in the Sichuan Province of China in Tibetans with a long history of drinking brick tea. The dental fluorosis investigation of 375 Tibetan children (213 males, 162 females) and 161 Han children (86 males, 75 females), 8-15 years of age, was carried out in Daofu County, Sichuan Province. According to the standard of the Chinese Health Ministry, a skeletal fluorosis survey of 658 Tibetans (264 males, 394 females) and 41 Hans (20 males, 11 females), all over 16 years old, was performed. The total fluoride intake and fluorosis were determined from a question--calculation method in all participants. The morbidities of dental fluorosis in Tibetan and Han children are 51.2% and 11.05%, respectively, and the indexes of dental fluorosis are 1.33 and 0.17 (chi 2 = 75.7, p < 0.01) respectively. The morbidity of skeletal fluorosis is 32.83% for Tibetan children and zero for the Han children. The fluoride intakes of Tibetan children and adults were 5.49 mg/person/day and 10.43 mg/person/day, respectively, in this area. Of total everyday fluoride intake, 94.2% by children and 94.4% by adults was from brick tea and zanba (r = 0.99).

Adolescent↗
PubMed1996

Effect of dietary iron concentration, age, and length of iron feeding on feed intake and tissue iron concentration of broiler chicks for use as a bioassay of supplemental iron sources.

Three experiments were conducted with day-old chicks to study the effects of dietary Fe concentration and age on Fe accumulation in tissues as an estimate of supplemental Fe bioavailability, and of delaying the time of initial high Fe supplementation up to 7 d of age on feed intake to 3 wk of age. In Experiment 1, chicks were fed a basal corn-soybean meal diet (188 mg/kg Fe, DM basis) or the basal supplemented with 400, 600, or 800 mg/kg added Fe as reagent grade FeSO4.7H2O for either 1, 2, or 3 wk. Dietary Fe depressed (P < 0.001) feed intake and body weight gain, especially at 3 wk. Kidney Fe concentrations increased linearly (P < 0.001) with increasing dietary Fe. Liver Fe concentration also increased linearly, but reached a plateau in birds fed 600 mg/kg Fe. Bone Fe increased linearly (P < 0.05) at 1 wk, but not at 2 or 3 wk. Liver and kidney Fe regressed on daily Fe intake had the best fit to a linear model at 2 wk. In Experiment 2, chicks were fed either a basal diet (320 mg/kg Fe, DM basis) continuously, the basal supplemented with 800 mg/kg added Fe as FeSO4.7H2O continuously, or were started on the control diet and switched to the high Fe diet on Day 3, 5, or 7. Feed intake was lower (P < 0.05) in birds started on Fe on Days 1 or 3, but delaying feeding of high Fe diets until Day 5 resulted in intake at 3 wk similar to that of birds fed the basal diet. In Experiment 3, the basal diet (123 mg/kg Fe) was fed to chicks for 6 d, then experimental diets were fed for 14 d. Diets were the basal or basal supplemented with 400, 600, or 800 mg/kg added Fe as reagent grade or feed grade Fe sulfate or an Fe methionine complex. When estimated from regression of log10 liver Fe concentration on total analyzed dietary Fe concentration, relative bioavailability was set at 100% for reagent grade Fe sulfate, and the feed grade sulfate was 92.3% and Fe methionine was 88.3%. Liver Fe concentrations may be useful criteria for determining Fe bioavailability and 2 wk of feeding was the optimal time required for such a bioassay. Delaying feeding high Fe diets until 5 d of age alleviated the decreased feed intake associated with high Fe diets.

Aging↗