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Biomedical subjects

Z L Chen

Publications and source records attributed to Z L Chen.

At least 73 records · Page 4Linked to original sources
PubMed1997

Neuronal death in the hippocampus is promoted by plasmin-catalyzed degradation of laminin.

Excess excitatory amino acids can provoke neuronal death in the hippocampus, and the extracellular proteases tissue plasminogen activator (tPA) and plasmin (ogen) have been implicated in this death. To investigate substrates for plasmin that might influence neuronal degeneration, extracellular matrix (ECM) protein expression was examined. Laminin is expressed in the hippocampus and disappears after excitotoxin injection. Laminin disappearance precedes neuronal death, is spatially coincident with regions that exhibit neuronal loss, and is blocked by either tPA-deficiency or infusion of a plasmin inhibitor, both of which also block neuronal degeneration. Preventing neuron-laminin interaction by infusion of anti-laminin antibodies into tPA-deficient mice restores excitotoxic sensitivity to their hippocampal neurons. These results indicate that disruption of neuron-ECM interaction via tPA/plasmin catalyzed degradation of laminin sensitizes hippocampal neurons to cell death.

Animals↗
PubMed1997

Piperbetol, methylpiperbetol, piperol A and piperol B: a new series of highly specific PAF receptor antagonists from Piper betle.

Piperbetol, methylpiperbetol, piperol A, and piperol B, isolated from Piper betle, selectively inhibited the washed rabbit platelet aggregation induced by platelet activating factor (PAF) in a concentration-dependent manner. The IC50 values of piperbetol, methylpiperbetol, piperol A, piperol B, and ginkgolide B were about 18.2, 10.6, 114.2, 11.8, and 4.8 mumol/l, respectively. The inhibitory potency of ginkgolide B was about 2.8, 1.2, 22.8, and 1.4 times higher than those of piperbetol, methylpiperbetol, piperol A, and piperol B. The concentration-response curve of PAF-induced platelet aggregation was shifted to the right by 50 mumol/l of piperbetol, methylpiperbetol, piperol A, piperol B, and ginkgolide B. The EC50 of PAF was increased by these compounds from 1.5 nmol/l to 14.3, 23.1, 2.4, 20.6, and 47.2 nmol/l, respectively. The compounds also inhibited the binding of [3H]-PAF to washed rabbit platelets with IC50 values of 8.7, 5.3, 88, 6.2, and 1.8 mumol/l. Correlating with the inhibitory potency for platelet aggregation, the inhibitory potency of ginkgolide B for binding of PAF was about 3.8, 1.9, 48, and 2.4 times higher than those of piperbetol, methylpiperbetol, piperol A, and piperol B. However, the aggregation of washed rabbit platelets induced by threshold ADP and arachidonic acid were unaffected by piperbetol, methylpiperbetol, piperol A, and piperol B. Furthermore, piperbetol, methylpiperbetol, piperol A, and piperol B had no effects on the cAMP contents in rest washed rabbit platelets. In conclusion, these data indicate that piperbetol, methylpiperbetol, piperol A, and piperol B are effective PAF receptor antagonists in vitro.

Animals↗
PubMed1996

Triterpenoid glycosides from Ilex kudincha.

Three new saponins, named kudinosides A, B and C, were isolated from the leaves of Ilex kudincha. On the basis of spectroscopic analysis and chemical transformation their structures were elucidated as 3-O-beta-D-glucopyranosyl-(1-->3)-[alpha-L-rhamnopyranosyl- (1-->2)]-alpha-L-arabinopyranosyl-beta-kudinlactone, 3-O-beta-D-glucopyranosyl-(1-->2)-beta-D-glucopyranosyl-(1-->3)-alpha-L- arabinopyranosyl-beta-kudinlactone and 3-O-beta-D-glucopyranosyl-(1-->2)-beta-D-glucopyranosyl-(1-->3)-[alpha-L -rhamnopyranosyl-(1-->2)]-alpha-L-arabinopyranosyl-beta-kudinla c tone.

Carbohydrate Conformation↗
PubMed1996

[Studies on nutritional effects of traditional Chinese tonics with strengthened nutrients on pregnant women and rats].

Clinical and Experimental studies on a mixture made of traditional Chinese tonics (such as Fructus Lycii, Rhizoma Dioscoreae and Arillus Longannae, etc.) and strengthened nutrients (such as iron, zinc and Calcium, etc.) were conducted in order to explore its nutritional and health promoting effects. (1) One hundred and three primiparous women were divided randomly into observed group and control group, results showed that the serum levels of iron, zinc, hemoglobin of observed group were all raised after treatment, these parameters and the concentration of iron in umbilical cord blood as well as body weight of new-born baby of the observed group were higher than that of control group (P < 0.05 or P < 0.01). (2) Results of experimental rats showed that the utilization rate, hemoglobin level, fetal growth and developing parameters of test group were all higher than that of control group significantly (P < 0.05 or P < 0.01). These results suggested that the nutrient mixture has a good nutritional and health promoting effect on pregnancy.

Animals↗
PubMed1995

Ontogeny of neuropsin mRNA expression in the mouse brain.

In our previous study, we found a novel gene encoding a serine protease termed neuropsin (NP) which exhibited activity-dependent gene expression or repression in the mouse hippocampus (Chen et al., 1995). In the present study, we examined the ontogeny of NP mRNA expression by in situ hybridization in the brain. Weak hybridization signals were also observed in the choroid plexus at this stage in addition to neuronal labeling. The signals continued to show this localization pattern until postnatal day 12. After embryonic day 18, the number of hybridization signals localized in the neurons of the forebrain limbic area were more predominant than those in the lower brainstem. NP gene expression spread in the anterior olfactory nucleus, hippocampus, septal nuclei, diagonal band of Broca, amygdala and limbic cortex successively from early embryonic to adult stage, though signals in the other brain regions were gradually decreased after birth. Thus, the widespread localization and two types of expression pattern, constitutive or transient, suggest that NP is a multiple functional protein involved in development, neuronal plasticity and cerebrospinal fluid production.

Animals↗
PubMed1995

Expression and activity-dependent changes of a novel limbic-serine protease gene in the hippocampus.

A novel murine cDNA which encodes a protein designated neuropsin was cloned. Northern and in situ hybridization analyses demonstrated that neuropsin mRNA is expressed specifically in the limbic system of mouse brain and is localized at highest concentration in pyramidal neurons of the hippocampal CA1-3 subfields. Direct hippocampal stimulation and kindling induced by amygdaloid stimulation caused a significant bilateral change in neuropsin mRNA level in the hippocampal pyramidal neurons. The activity-dependent changes and the specific localization indicate that neuropsin is involved in hippocampal plasticity.

Amino Acid Sequence↗
PubMed1995

Morphine inhibited respiratory burst of neutrophils and scavenged oxygen free radicals.

AIM: To study the effects of morphine on active oxygen free radicals. METHOD: Chemiluminescence method was used to measure (a) active oxygen generation induced by respiratory burst of neutrophils from human blood stimulated with phorbol myristate acetate (PMA), (b) Superoxide anion (O2.-) induced by xanthine-xanthine oxidase system, (c) hydroxyl radical (.OH) generated by ascorbic acid (AA)-Cu(2+)-zymosan, and (d) the release of H2O2. RESULTS: The (a), (b), (c), and (d) were scavenged by morphine and their median inhibitory concentrations (IC50 and 95% confidence limits) were 21.1 (13.0-34.0), 54.1 (50.0-58.5), 224.0 (128.2-390.8), and 66.9 (62.9-71.0), nmol L-1, respectively. CONCLUSION: The immunosuppressant effect of morphine was related to its free radicals scavenging action.

Adult↗
PubMed1994

Basal magnocellular and pontine cholinergic neurons coexpress FGF receptor mRNA.

By in situ hybridization histochemistry, fibroblast growth factor receptor gene (flg)-expressing neurons were newly identified in the basal magnocellular nuclei (the vertical and horizontal limbs of the diagonal band, and Meynert's nucleus). The present study also confirmed flg localization in the laterodorsal tegmental nucleus and the pedunculopontine tegmental nucleus of the pons. Immuno- and in situ hybridization histochemistry on the same sections demonstrated that choline acetyltransferase and flg were colocalized in single neurons of the diagonal band, Meynert's nucleus and the pontine tegmental areas. The results suggest that a significant number of the basal magnocellular and a majority of the mesopontine cholinergic neurons are directly affected by fibroblast growth factors (FGF) via FGF receptor gene.

Animals↗
PubMed1993

Frequency and distribution of occult micrometastases in lymph nodes of patients with non-small-cell lung carcinoma.

BACKGROUND: Accurate assessment of the presence and absence of tumor in the regional lymph nodes is critical in assessment of prognosis for patients with lung cancer. Development of sensitive immunohistochemical techniques and specific monoclonal antibodies has increased our capacity, in melanoma and breast cancer, to detect small groups of tumor cells or even single tumor cells in lymph nodes that appear to be tumor free in conventionally stained sections. PURPOSE: This retrospective study was designed to assess whether use of a polyclonal antikeratin reagent in immunohistochemical analysis offers any advantage over conventional histopathology in detection of regional lymph node metastases in non-small-cell lung cancer. METHODS: Paraffin-embedded tissue sections from regional lymph nodes of 65 patients with non-small-cell lung cancer were studied. We examined tissue from 588 nodes of 60 patients with a diagnosis of disease confined to the lung and from 72 nodes of five patients with a diagnosis of metastasis to some nodes. A polyclonal antikeratin antibody was applied to the lymph node tissue sections, using the avidin-biotin complex immunoperoxidase technique. RESULTS: Single tumor cells and small clusters of tumor cells (occult micrometastases) not visible on routine evaluation were readily detected in 38 (63%) of the 60 patients whose nodes appeared to be negative on examination of hematoxylin-eosin-stained slides. In the five patients with a diagnosis of node-positive non-small-cell lung cancer, five (10%) of 51 nodes that were tumor free on conventional examination contained metastases. Metastatic tumor cells were most often located in the subcapsular or medullary sinuses. The lymph nodes that contained occult tumor cells were those located nearest to the tumor, mainly in peribronchial and hilar locations. The median survival of patients with occult metastases (1977 days) was shorter than that of patients whose nodes contained no tumor (2456 days) but was longer than that of patients whose nodes contained metastases detectable on hematoxylin-eosin-stained slides (927 days). CONCLUSIONS: Our results suggest that, in patients with non-small-cell lung cancer, metastatic involvement of regional lymph nodes is more frequent than was previously determined by the conventional histologic method and substantially more frequent than in other tumor types, such as melanoma and breast cancer. IMPLICATIONS: The high frequency of occult nodal metastases in non-small-cell lung cancer makes it clear that, without immunohistochemistry, disease is understaged in many patients. Therefore, it seems essential that immunohistochemical evaluation of the lymph nodes be undertaken in clinical trials.

Adult↗
PubMed1993

Preclinical pharmacology of the antitumor agent O-6-methylguanine in CDF1 mice.

O-6-methylguanine (O6-mG), a guanine analog recently shown to be a potent inhibitor of alkylguanine-DNA alkyltransferase, has been found to potentiate the antitumor activity of nitrosoureas, in particular, carmustine (BCNU), in resistant cell lines (HT-29 mer+) and is targeted for development as a modulating agent with chloroethyl nitrosoureas. A high-performance liquid chromatography (HPLC) assay of O6-mG in plasma has been developed using a microC18 reverse-phase column. O6-mG and the internal standard deoxyguanosine (dGuo) were eluted with a linear gradient of from 15% to 35% methanol in 0.5 M ammonium acetate (pH 6.5) at a flow rate of 1 ml/min. The assay was linear over a 4-log concentration range with a detection limit of 0.1 microgram/ml. The within-run and between-run coefficients of variation (CV) were found to be 8.1% and 9.3%, respectively. The pharmacokinetics (PK) of O6-mG were investigated in healthy CDF1 mice following separate i.v. and i.p. administrations. At 20 mg/kg i.v., plasma O6-mG gave a biexponential profile with a terminal half-life (t1/2) of 24 min and a total clearance (CLT) of 23.7 ml min-1 kg-1. Higher doses (40-80 mg/kg) revealed a fluctuating third phase, probably due to enterohepatic cycling. Dose-dependent kinetics as measured by CLT and area under the plasma-concentration curve (AUC) values were also seen. Following i.p. dosing, O6-mG was completely absorbed and available to the circulation. No acute toxicity was observed in the animals, except for mild sedation, a possible side effect of the 10% ethanol used in the formulation. Studies on the cellular metabolism of highly purified [3H]-O6-mG have shown that the compound is not anabolized by a human lymphoblastoid cell line (CEM). Biochemistry studies have shown that the parent molecule is inactivating the alkylguanine-DNA alkyltransferase (AGT), thus exerting its pharmacological effect.

Animals↗
PubMed1993

Identification and regional localization of a human IMP dehydrogenase-like locus (IMPDHL1) at 16p13.13.

Sequence-tagged sites (STSs) are versatile chromosomal markers for a variety of genome mapping efforts. In this report, we describe a randomly generated STS (323F4) from human chromosome 16 genomic DNA that has 90.0% sequence identity to the type I human inosine-5'-monophosphate dehydrogenase (IMPDH1) gene and 72% identity to the type II human inosine-5'-monophosphate dehydrogenase (IMPDH2) gene. Additional sequencing by primer walking has provided a total of 1380 bp of the human chromosome 16 sequence. The IMPDH-like sequence 323F4 was regionally localized by PCR analysis of a panel of somatic cell hybrids containing different portions of human chromosome 16 to 16p13.3-13.12, between the breakpoints found in hybrids CY196/CY197 and CY198. This regional mapping assignment was further refined to subband 16p13.13 by high-resolution fluorescence in situ hybridization using cosmid 323F4 as a probe. We conclude that a third, previously undescribed IMPDH locus, termed IMPDHL1, exists at human chromosome 16p13.13.

Animals↗
PubMed1993

Ideal therapeutic range of cyclosporine in whole blood in kidney-transplanted patients.

Two hundred and eighty-seven renal-transplanted recipients treated with cyclosporine were monitored for their cyclosporine trough blood level periodically. Based on the monitor results, we now can define the ideal therapeutic range of cyclosporine in whole blood as follows: 500-600 ng/ml in the first week of post-transplantation, 600-800 ng/ml in the second week to sixth month of post-transplantation, 400-600 ng/ml in the seventh to twelfth month of post-transplantation and 350-400 ng/ml 1 year after post-transplantation.

Adolescent↗
PubMed1993

Pilot study to determine acceptability and ability of heat-killed Mycobacterium leprae plus BCG (HKML+BCG) vaccine to induce skin test conversion.

Although local reactions, including erythema, induration and ulcers, appeared in every patient after the injection of the combined HKML+BCG vaccine, they were accepted by the patients. There was no tendency for the local reaction to become aggravated after repeated vaccination. However, systemic reactions, mainly iridocyclitis and complaint of numbness of the fingers and toes, became quite common after the 5th vaccination and therefore significantly reduced the acceptability of vaccine by injection. It seems that repeated vaccination might activate the iridocyclitis, but the relationship between the complaint of numbness and vaccination has not been well established. Neither typical ENL nor reversal reaction had been observed throughout the trial. A significant proportion of patients converted to SMLA positivity after repeated vaccination. However, it seems the positive status was not stable as many of them reverted to negative after the following vaccination. After the 7th vaccination, the positive conversion rate to SMLA-I was 45% and to SMLA-II was 35%. After the 8th vaccination, 66.7% of patients converted to Mitsuda reaction positive, which has been confirmed by histopathological examination. Nevertheless, further follow-up is required in order to determine whether or not such conversion will be of a long duration. The reactions to SMLA-I and SMLA-II were associated but only correlated at a moderate level. Overall, the positive conversion rate to SMLA-I was significantly higher than that to SMLA-II after repeated vaccination. Neither the early reaction nor the late (Mitsuda) reaction of the lepromin test were correlated to either SMLA reaction. The repeated vaccination of HKML+BCG vaccine did not affect the weakly-positive anti-PGL-1 Mycobacterium leprae antibody level seen in the skin-smear negative lepromatous patients participating in this study.

Adult↗
PubMed1993

[Mortality rate and causes of death of premature and low-birth-weight infants in 18 cities].

The investigation at 19 hospitals in 18 cities showed that the incidence of premature and low-birth-weight (LBW) infant in live births was 4.9% and 5.1% respectively. The mortality rate was as high as 85.5/1000 and 97.7/1000 and the deaths accounted for 45.9% and 54.5% of total neonatal deaths respectively. The male infant's mortality rate was higher than the female; the twins' and triplets' was higher than the single births'. The mortality was mainly attributed to the preterm, LBW and related diseases. The first six causes of deaths were respiratory diseases, prenatal asphyxia, infection, scleredema congenital malformation and intracranial hemorrhage. The approaches for reducing the mortality rate of premature and LBW infants were discussed.

Cause of Death↗
PubMed1992

Human alpha 2-HS-glycoprotein/bovine fetuin homologue in mice: identification and developmental regulation of the gene.

Human alpha 2-HS-glycoprotein (AHSG) is a plasma protein synthesized in liver and selectively concentrated in bone matrix. It has been reported to be involved in bone formation and resorption as well as immune responses. Recently, AHSG was found to be the species equivalent protein of fetuin, the major fetal serum protein in cattle and sheep. The function and regulation of AHSG/fetuin in different species are not understood. We have isolated a liver cDNA clone that encodes the human AHSG/bovine fetuin homologue in the mouse. The AHSG/fetuin gene may have a role in differentiation since it is expressed in mouse limb buds and brain only at certain stages during development. Mouse liver AHSG/fetuin mRNA was present at low level at 12 days gestation but its level increased during the late part of gestation and peaked between 1 to 3 months after birth. The regulation of mouse AHSG/fetuin synthesis during development was found to be significantly different from that of sheep and bovine fetuin. Compared to fetuin, which is reduced in adult to 1 to 2% of the fetal level, mouse AHSG synthesis subsides only 50% 4 months after birth.

Amino Acid Sequence↗