Search PubMed⌕ Search

Biomedical subjects

Z Chen

Publications and source records attributed to Z Chen.

At least 1,423 records · Page 79Linked to original sources
PubMed1992

Beta-blocker therapy in acute myocardial infarction: evidence for underutilization in the elderly.

PURPOSE: To assess the impact of patient age on the use of beta-blocker therapy in the management of acute myocardial infarction. PATIENTS AND METHODS: The population studied consisted of 4,762 patients hospitalized with validated acute myocardial infarction in 16 hospitals in the Worcester, Massachusetts, Standard Metropolitan Statistical Area during the years 1975, 1978, 1981, 1984, 1986, and 1988. Logistic regression analysis was employed to control for relevant demographic and clinical variables in evaluating the independent effect of patient age as a determinant of receipt of beta-blocker therapy during the hospitalization. RESULTS: A consistent trend toward reduced use of beta-blocker therapy in older patients was demonstrated. After adjustment for demographic and clinical variables (gender; prior history of angina, hypertension, or diabetes mellitus; myocardial infarction characteristics; complications including congestive heart failure and shock; and use of digoxin and diuretics), odds ratios for receipt of beta-blocker therapy relative to patients less than 55 years of age were 0.61 for those 55 to 64; 0.52 for those 65 to 74; 0.36 for those 75 to 84; and 0.26 for those 85 or older. Analyses performed for each study year demonstrated results consistent with those for the overall study population. CONCLUSION: The results of this population-based study suggest that there are substantial opportunities for expanded use of beta-blocker therapy in elderly patients who have sustained an acute myocardial infarction.

Adrenergic beta-Antagonists↗
PubMed1992

Intention and outcome: key components of causal structure facilitating mapping in children's analogical transfer.

The consequences of two key features of causal structure in source stories, intention and positive outcome, for analogical transfer were examined in kindergarten and second graders. In Experiment 1, children received either structure-complete, structure-incomplete, or irrelevant source stories. Structure-incomplete stories lacked either the intention to solve a problem (a goal-directed component), evidence of a successful consequence (an outcome-related component), or both as part of the solution activity described in source stories. Evidence for transfer was obtained for second graders when a goal-directed component, and to a lesser extent, an outcome-related component were connected to the solution action in source stories. Differences among conditions for kindergartners were less evident, although they revealed a pattern of performance similar to the second graders. A second experiment was conducted to determine whether memory and an orientation to use the source story information might account for these findings. Efforts to ensure memory for and hints to use information in the source stories, however, did not benefit solution transfer when intention and positive outcome were absent. These results suggest that a complete causal structure, including goal and outcome, in source stories augments transfer in young children by promoting mapping of the analogical relationship between source stories and the target problem.

Achievement↗
PubMed1992

Respiratory-associated rhythmic firing of midbrain neurons is modulated by vagal input.

We recorded phrenic nerve activities and single unit firings of mesencephalic neurons in 19 decerebrate, paralyzed and ventilated cats, in which the spinal cord had been transected at C7-T1 and carotid sinus nerves cut but vagus nerves left intact. After we had found neurons with respiratory-associated rhythmic activity, we tested the effect of changing pulmonary vagal input by (1) stopping and restarting the ventilator; (2) changing the ventilator's tidal volume; (3) progressively cooling the vagus nerves to 6-7 degrees C; and (4) vagal section. All methods of testing yielded results that showed that vagal input, probably from pulmonary stretch receptors, tonically inhibits the respiratory-associated firing of the mesencephalic neurons by a direct mechanism that is independent of a vagal effect on medullary respiratory drive. We have suggested that these neurons are involved in the mechanism that conveys information about respiration to the cortex where it may be interpreted as the sensation of dyspnea. If so, movement and increased expansion of the lungs can be expected to lessen the sensation.

Animals↗
PubMed1992

Respiratory-associated thalamic activity is related to level of respiratory drive.

We recorded phrenic nerve activity and thalamic single unit firing in unanesthetized, suprathalamically decerebrated, paralyzed and ventilated cats, in which vagi and carotid sinus nerves (CSN) had been ablated. Seventy-six (14%) of 545 neurons in regions of the thalamus related to the ascending reticular system, which had been tonically firing at low respiratory drives, developed rhythmic increases of firing associated with each respiration when drive had been increased by CSN stimulation or hypercapnia. The increases of neuronal firing occurred in late inspiration/post-inspiration but sometimes lasted into expiration; the magnitude of change was graded according to the magnitude of respiratory activity. Thalamic neurons also fired with a rhythm related to ventilator-induced chest expansion, some units showing both the respiratory-associated and the ventilator-related rhythms. Simultaneously recorded mesencephalic and thalamic neurons developed similar rhythms when drive was increased. We suggest that these neuronal activities reflect the conveyance of information about respiration to the cortex, where it may lead to the sensation of dyspnea and perhaps to arousal.

Action Potentials↗
PubMed1992

Cytogenetic and FISH studies of abnormal X chromosomes in a patient with ANLL.

We report a case of idic(X)(q13),r(X)(p22q13), and del(X)(:p11-->cen-->q11:) in a 71-year-old female patient with de novo acute nonlymphocytic leukemia (ANLL), FAB-M4. The abnormal X chromosomes of this patient were identified cytogenetically by G-banding technique and were further confirmed by fluorescence in situ hybridization (FISH) using an alpha-satellite probe to chromosome X centromere. The features of this are compared with other cases reported in the literature.

Aged↗
PubMed1992

Lactate dehydrogenase-elevating virus (LDV): subgenomic mRNAs, mRNA leader and comparison of 3'-terminal sequences of two LDV isolates.

The 3'-terminal 1314 nucleotides of the genome of one isolate of lactate dehydrogenase-elevating virus, LDV-P, has been derived by sequence analyses of cDNAs from several genomic libraries and compared to that of another LDV isolate, LDV-C (Godeny et al. (1990) Virol. 177, 768-771). The 3'-non-coding segment of 80 nucleotides of the two LDV genomes is identical, whereas marked, but varying nucleotide and amino acid divergence is apparent in the three upstream overlapping open reading frames (ORF). The third ORF from the 3'-end exhibits only 82% nucleotide and 90% amino acid identity, whereas the 3'-terminal ORF, which encodes the nucleocapsid protein, exhibits approximately 99% amino acid identity. The second 3'-terminal ORF encodes an 18.8 kDa protein which lacks N-glycosylation sites but possesses 2 or 3 potential transmembrane helices in the N-terminal half of the molecule. A similar membrane organization is observed for the corresponding protein of equine arteritis virus and the M protein of mouse hepatitis virus. The sequence analyses combined with Northern hybridization analyses of RNA from LDV-infected macrophages and spleens of LDV-infected mice indicate that the three ORFs encoded by the 3'-terminal end of the LDV genome are expressed via the three smallest mRNAs (mRNAs 6-8) of the seven subgenomic mRNAs of LDV (mRNAs 2-8), which range in size from about 0.8 to 3.6 kb. All mRNAs have been shown to carry poly(A)-tracts and a common leader sequence. The seven mRNAs were produced in infected macrophage cultures concomitantly with genomic LDV RNA. Maximum LDV RNA synthesis was observed between 6 and 8 h post-infection. The same seven subgenomic mRNAs were detected in macrophages infected with three different isolates of LDV, but different relative amounts of some of the mRNAs were produced. The relative proportions of molecules of mRNAs 1-8 present in 6 h LDV-P-infected macrophages were about 13, 5, 5, 8, 6, 11, 11 and 27% of the total, respectively.

Amino Acid Sequence↗
PubMed1992

Digital road mapping image--a novel fluoroscopic real-time guide for selective transcervical catheterization in the treatment of proximal tubal obstruction.

Ten infertile women 20 to 40 years of age, with a standard HSG diagnosis of unilateral proximal tubal obstruction, underwent a transvaginal catheterization and recanalization of the fallopian tubes. To set a fluoroscopic real-time guidance technique for improving the results of transvaginal catheterization and recanalization of the fallopian tubes and to increase its marginal safety, catheterization was performed under digital road mapping guidance. Transcervical catheterization resulted in an immediate patency of the obstructed tube in all 10 women. Three women conceived 2 to 3 months after the procedure. The improved catheterization technique enables good results in the diagnosis and treatment of proximal tubal obstructions.

Adult↗
PubMed1992

Primary reconstruction of the mandibular alveolar ridge following resection.

Standard techniques of mandibular reconstruction aim at the restoration of function. However, the height and shape of the alveolar ridge are often neglected and reconstruction often results in difficulty in subsequent denture wear. Immediate reconstruction of the alveolar process with particulate autologous iliac bone is described, a technique used in 10 patients since 1978.

Adolescent↗
PubMed1992

Osmotin gene expression is posttranscriptionally regulated.

Accumulation of both osmotin mRNA and osmotin protein in tissues of tobacco (Nicotiana tabacum L. var Wisconsin 38) is subject to complex developmental control. Osmotin was found to be most abundant in tobacco roots and in tissues of the outer stem comprised primarily of epidermis, and it was less abundant in the corolla. It was a minor protein in other tissues and was undetectable in some tissues, including those of developing and mature seeds. The mRNA abundances did not always reflect the amount of protein accumulation because in some tissues high levels of mRNA but not protein were measured and vice versa. Accumulation of osmotin mRNA but not protein occurred in some plant tissues due to treatment with abscisic acid, wounding, and tobacco mosaic virus infection. Ethylene induced the accumulation of osmotin mRNA and, to a small extent, protein in seedlings, but was ineffective with cultured cells. Exposure of cultured cells and plants to NaCl caused high levels of both mRNA and the protein to accumulate. Thus, the accumulation of osmotin mRNA is controlled developmentally and by at least five hormonal or environmental signals. However, posttranscriptional processes can limit osmotin accumulation.

Journal Article↗
PubMed1992

Induction of a Putative Ca-ATPase mRNA in NaCl-Adapted Cells.

A cDNA clone was isolated that encodes the partial sequence of a putative endoplasmic reticulum Ca(2+)-ATPase of tobacco. The 1.497-kb insert had an open reading frame of 1.149 kb. The deduced peptide had the greatest homology to the endoplasmic reticulum Ca(2+)-ATPases of Drosophila and Artemia, followed by the mammalian and avian enzymes (SERCA2 and 3). The cDNA insert hybridized to a single mRNA of 4.4 kb from tobacco cultured cells or plant tissues. The level of this transcript was induced about 2-fold by NaCl shock in 428 mm NaCl-deadapted tobacco cells that were maintained in medium without salt, but not in unadapted cells. The level of this transcript was 3- to 4-fold higher in 428 mm NaCl-adapted cells growing in salt than in unadapted cells growing without salt.

Journal Article↗
PubMed1992

Highly polymorphic XbaI RFLPs of the human 21-hydroxylase genes among Chinese.

A highly polymorphic XbaI restriction site flanking the human 21-hydroxylase genes (21-OHA and 21-OHB) was found with the probe pC21/3c, the cDNA of the 21-hydroxylase gene. From the results of RFLP analysis of 10 subjects with congenital adrenal hyperplasia (CAH) owing to 21-hydroxylase deficiency and their parents, at least four polymorphic fragments (30 kb, 27 kb, 25 kb, and 15 kb) resulting from cleavage at the polymorphic endonuclease sites outside the genes were found, and at least 10 different polymorphic patterns were observed among Chinese. These results indicate that these polymorphic loci are very informative for prenatal diagnosis of 21-hydroxylase deficiency.

Adrenal Hyperplasia, Congenital↗
PubMed1992

Microcarrier culture of fish cells and viruses in cell culture bioreactor.

This article deals with the culture of grass carp (Ctenopharyngodon idellus) lip and embryo cells on Cytodex 3 and GT-2 microcarriers in a 1.5-L cell culture bioreactor to propagate grass carp hemorrhage virus. The cells and viruses were successfully cultivated at 26 degrees C, pH 7.0, and dissolved oxygen 40% of air saturation. The cell density achieved was as high as 7.4 x 10(6) cells/mL, and the virus titre reached 6.75 log LD50/0.5 mL from an initial 3.00 log LD50/0.5 mL. The results present broad prospects for fish virus vaccine production.

Animals↗
PubMed1992

The anti-tumor effect of a small polypeptide from Coriolus versicolor (SPCV).

A new small polypeptide was isolated from the crude extraction of polysaccharide peptide of Coriolus versicolor (Cov-1) by HPLC and CIEF. It has a smaller molecular weight (10K) compared with that of PSP (100K) and was named small peptide of Coriolus versicolor, SPCV. It was found that SPCV possesses potent cytotoxic effect on human tumor cell lines of HL-60, LS174-T, SMMU-7721, and SCG-7901. The IC50 of SPCV on HL-60 was 30 micrograms/ml. The inhibition rates of leukemia cells and SCG-7901 were significantly higher in SPCV treated group than that in PSP and PSK groups. SPCV also has immunopotentiating effect as it increased WBC and IgG levels. Pretreatment of SPCV for two weeks decreased the incidence of tumor mass in nude mice inoculated with tumor cells.

Animals↗
PubMed1992

RARA and PML genes in acute promyelocytic leukemia.

Acute promyelocytic leukemia (APL) is characterized by a specific chromosome translocation t(15;17). Recently, using molecular biology techniques, a number of laboratories have demonstrated that the gene coding for the retinoic acid receptor alpha (RARA), normally located on chromosome 17, is disrupted by the t(15;17) and fused with the PML gene on chromosome 15. The chromosome 17 breaks were mapped consistently within the second intron of the RARA gene while the chromosome 15 breaks were clustered in two limited regions within the PML gene. Molecular cloning and sequence analysis of the PML gene demonstrated a complex splicing pattern and this gene may encode a transcription factor. Different isoforms of the PML-RARA fusion transcripts were discovered which are produced as a result of distinct PML gene rearrangements. Sequence analysis of the reciprocal products of the translocation t(15;17) in some APL cases suggested the implication of topoisomerase II in mediating the DNA recombination. The RT/PCR procedure has been established to characterize the expression patterns of the PML-RARA fusion gene and to detect minimal residual disease (MRD). The biological activity of the PML-RARA fusion gene and its isoforms should be further explored.

Carrier Proteins↗
PubMed1992

[A randomized control trial of isovolemic hemodilution therapy in cor pulmonale].

The hemorheologic properties are obviously abnormal in patients with cor pulmonale (CP), presenting as high hematocrit (HCT), hyperviscosity and hyper-viscoelasticity. Twenty patients suffering from CP with polycythemia were randomized into either an isovolemic hemodilution (IHD) group or control group. In the IHD group, 10 patients were treated by routine therapy combined with IHD. The other 10 patients in the control group were treated by routine therapy only. The results demonstrated that after treatment in IHD group, all viscoelasticity property parameters except eta p were decreased significantly. Oxygen delivery, oxygen transport capacity, and stroke volume and cardiac output were increased. Mean pulmonary artery pressure and total pulmonary resistance were decreased. However, in the control group only HCT and eta 0.512 were decreased after treatment. The viscosity and eta' of the whole blood in IHD group were decreased more markedly than those in the control group. IHD was well tolerated in most of the patients. There were no complications or side effects. Thus, IHD is a safe, effective and acceptable therapy, and it may play a role in the treatment of cor pulmonale.

Adult↗