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Biomedical subjects

L Song

Publications and source records attributed to L Song.

At least 163 records · Page 9Linked to original sources
PubMed1996

Substance P modulates human immunodeficiency virus replication in human peripheral blood monocyte-derived macrophages.

Substance P (SP), a member of the tachykinin family of neuropeptides, is an important immunomodulator of lymphocyte and monocyte/macrophage function. We have examined the effects of SP on human immunodeficiency virus type 1 (HIV-1) infection of peripheral blood monocyte-derived macrophages (MDMs) in vitro. Human monocytes isolated by Ficoll gradient followed by adherence were maintained in vitro for 10 days and infected with HIV-1. The addition of SP resulted in a 2- to 8-fold-enhanced HIV-1 expression in the MDMs isolated from 7 of 13 healthy donors as determined by reverse transcriptase (RT) activity and p24 protein expression assays, as compared to control cultures incubated with HIV-1 alone. There was no correlation observed, however, between SP-stimulated TNF production and HIV-1 expression in MDMs obtained from a subset of these donors. These effects of SP on HIV-1 expression in MDMs in vitro may have in vivo implications relevant to modulation of monocyte/macrophage functions, to HIV-1 infection of monocytes/macrophages, and to the immunopathogenesis of HIV-1 infection.

Cells, Cultured↗
PubMed1996

Induction of HIV-1 expression in chronically infected promonocytic cells cocultured with human lung fibroblasts.

The interaction between a chronically human immunodeficiency virus type 1 (HIV-1)-infected promonocytic line (U1) and a normal human embryonic lung fibroblast line (MRC-5) on HIV-1 expression was investigated. Coculture of U1 cells with MRC-5 cells induced HIV-1 reverse transcriptase (RT) activities 40- to 50-fold higher than those of parallel control cultures of U1 cells. Culture of U1 cells in the presence of media conditioned by MRC-5 cell culture supernatants resulted in a 30- to 40-fold greater HIV-1 RT activity over a 6-day period. HIV-1 RT activity, however, was not increased in the chronically infected T lymphocyte cell line (ACH-2) by either coculture with MRC-5 cells or when cultured in the MRC-5 cell culture supernatant-conditioned media. A polyclonal antibody against interleukin-6 (IL-6) blocked HIV-1 induction in the U1 cells by MRC-5 culture supernatants, indicating that IL-6 plays an important role in the HIV-1 induction. The magnitude of HIV-1 induction by the MRC-5 cell culture supernatant-conditioned media was proportional to the concentration of IL-6. In addition, the supernatants from three other normal human lung fibroblast (HLF) cell lines induced HIV-1 RT expression in U1 cells. Thus, normal unstimulated HLFs stimulate HIV-1 expression in chronically infected promonocytic cells by secreting IL-6, suggesting that the interaction of HLFs and macrophages may play an important role in the development of HIV-1 infection in the lungs.

Antibodies↗
PubMed1996

Influence of the triplet excited state on the photobleaching kinetics of fluorescein in microscopy.

The investigation in this report aimed at providing photophysical evidence that the long-lived triplet excited state plays an important role in the non-single-exponential photobleaching kinetics of fluorescein in microscopy. Experiments demonstrated that a thiol-containing reducing agent, mercaptoethylamine (MEA or cysteamine), was the most effective, among other commonly known radical quenchers or singlet oxygen scavengers, in suppressing photobleaching of fluorescein while not reducing the fluorescence quantum yield. The protective effect against photobleaching of fluorescein in the bound state was also found in microscopy. The antibleaching effect of MEA let to a series of experiments using time-delayed fluorescence spectroscopy and nanosecond laser flash photolysis. The combined results showed that MEA directly quenched the triplet excited state and the semioxidized radical form of fluorescein without affecting the singlet excited state. The triplet lifetime of fluorescein was reduced upon adding MEA. It demonstrated that photobleaching of fluorescein in microscopy is related to the accumulation of the long-lived triplet excited state of fluorescein and that by quenching the triplet excited state and the semioxidized form of fluorescein to restore the dye molecules to the singlet ground state, photobleaching can be reduced.

Biophysical Phenomena↗
PubMed1996

The phosphoinositide signal transduction system is impaired in bipolar affective disorder brain.

The function of the phosphoinositide second messenger system was assessed in occipital, temporal, and frontal cortex obtained postmortem from subjects with bipolar affective disorder and matched controls by measuring the hydrolysis of [3H]phosphatidylinositol ([3H]PI) incubated with membrane preparations and several different stimulatory agents. Phospholipase C activity, measured in the presence of 0.1 mM Ca2+ to stimulate the enzyme, was not different in bipolar and control samples. G proteins coupled to phospholipase C were concentration-dependently activated by guanosine 5'-O-(3-thiotriphosphate) (GTP gamma S) and by NaF. GTP gamma S-stimulated [3H]Pl hydrolysis was markedly lower (50%) at all tested concentrations (0.3-10 microM GTP gamma S) in occipital cortical membranes from bipolar compared with control subjects. Responses to GTP gamma S in temporal and frontal cortical membranes were similar in bipolars and controls, as were responses to NaF in all three regions. Brain lithium concentrations correlated directly with GTP gamma S-stimulated [3H]Pl hydrolysis in bipolar occipital, but not temporal or frontal, cortex. Carbachol, histamine, trans-1-aminocyclopentyl-1,3-dicarboxylic acid, serotonin, and ATP each activated [3H]Pl hydrolysis above that obtained with GTP gamma S alone, and these responses were similar in bipolars and controls except for deficits in the responses to carbachol and serotonin in the occipital cortex, which were equivalent to the deficit detected with GTP gamma S alone. Thus, among the three cortical regions examined there was a selective impairment in G protein-stimulated [3H]Pl hydrolysis in occipital cortical membranes from bipolar compared with control subjects. These results directly demonstrate decreased activity of the phosphoinositide signal transduction system in specific brain regions in bipolar affective disorder.

Adenosine Triphosphate↗
PubMed1996

Serum concentrations of human chorionic gonadotrophin and immunoreactive inhibin in early pregnancy and recurrent miscarriage: a longitudinal study.

Serum concentrations of immunoreactive inhibin (ir-inhibin) and human chorionic gonadotrophin (HCG) have been measured during the first trimester in a longitudinal study of pregnant women attending a recurrent miscarriage clinic. In 30 singleton pregnancies (Group 1) that continued successfully to term, the median concentration of ir-inhibin initially declined from 1,140 pg/mL at week 4-5 then rose back to comparable values between weeks 7 and 10 but to decline again to reach the significantly lower level of 840 pg/mL (p < 0.01) at week 15-16. Serum levels of HCG showed the classical profile of normal pregnancy reaching a median peak value of 65,600 IU/L (1st IRP) at week 8-9. In 7 pregnancies that miscarried but earlier had evidence on ultrasound of an active fetal heart, HCG levels in the first 9 weeks were consistently below the 10th percentile for Group 1 pregnancies (p < 0.001). Levels of ir-inhibin were also suppressed but to a lesser extent. In 6 of 7 a fetal pregnancies, HCG levels during the first 9 weeks were again markedly subnormal. The levels of ir-inhibin varied between high normal and subnormal. In none of the pregnancy groups was a correlation found between ir-inhibin and HCG concentrations. In a single pregnancy with an anencephalic fetus, while levels of ir-inhibin and HCG were not depressed, peak values were not reached until week 12. The study shows that the level of ir-inhibin in the maternal serum in early pregnancy is of little value as a prognostic indicator of pregnancy outcome. It confirms that a subnormal HCG level is a useful predictor of early pregnancy failure.

Abortion, Habitual↗
PubMed1996

Expression of aminopeptidase A, an angiotensinase, in glomerular mesangial cells.

Glomerular mesangial cells are known to express angiotensin II type 1 receptors and contract in response to circulating and/or locally produced angiotensin II. In addition, stimulation of mesangial cell matrix protein synthesis by elevated levels of angiotensin II is known to contribute to the development of glomerulosclerosis. Previously, we reported that mesangial cells were positively immunostained with antiserum directed against aminopeptidase A, the principal angiotensinase in the metabolism of angiotensin II. Here we demonstrate directly that aminopeptidase A is expressed in mesangial cells cultured from rat kidney. First, cultured mesangial cells had measurable aminopeptidase A enzymatic activity. Second, immunoblots for aminopeptidase A were positive for isolated glomeruli and mesangial cells, although two bands were seen for mesangial cells (approximately 138 and 144 kD), and only the larger band was seen for isolated glomeruli and kidney. Third, Northern blot hybridizations of total RNA from mesangial cells or kidney were positive and labeled similarly sized bands. Fourth, reverse transcription-polymerase chain reaction amplification of mesangial cell total RNA yielded a partial cDNA of the expected size that was confirmed by sequencing to be identical to rat kidney aminopeptidase A. These results indicate that aminopeptidase A is expressed within mesangial cells. These results further suggest that metabolism of angiotensin II by aminopeptidase A could play a protective role in minimizing the adverse effects of angiotensin II stimulation of mesangial cells.

Aminopeptidases↗
PubMed1996

[Detection of placental alkaline phosphatase in ovarian cancer].

OBJECTIVE: To establish a method for diagnosis of malignant tumors by determination of the placental alkaline phosphatase (PLAP) in serum. METHODS: A solid phase enzyme immunoassay was adopated by an antibody against PLAP. PLAP in serum of 81 patients with malignant tumor and 86 healthy people as control were determined. RESULTS: In the control group, the PLAP activity showed deviative distribution, the 95th percentile values of PLAP in control group was 3.8U/L. If this value served as normal cut-off line, 18 cases among 81 patients with malignant tumors were positive. The positive rate was 22.2%, but the positive rates in ovarian cancer was 61.9%. CONCLUSIONS: The increasing of serum PLAP may be helpful for the diagnosis of malignant tumors especially ovarian cancer.

Alkaline Phosphatase↗
PubMed1996

The central distribution of adrenomedullin and its effects on blood pressure and heart rate in rats.

The present study was designed to make certain whether there exists adrenomedullin (ADM) in the rat central nervous system and evaluated the hemodynamic actions of intracerebroventricular administration (ICVA) of human ADM[13-52]. By immunohistochemistry (ABC method). We found that there was a discrete localization of ADM-positive immunoreactivity in the rat central system including cerebral cortex, paraventricular tissues, hypothalamus, cerebella cortex, mesencephalon and medulla oblongata. By reverse transcription-polymerase chain reaction (RT-PCR) analysis, rat ADM mRNA was found to be expressed in rat brain. These above results of immunohistochemistry and RT-PCR suggest that ADM exists in the rat brain. We also found that centrally administered ADM[13-52] in a dose of 0.4 to 3.2 nmol/kg provoked marked, prolonged and dose-dependent increases in mean arterial blood pressure (MABP) and heart rate (HR). To clarify the mechanisms of the hemodynamic changes induced by centrally administered ADM [13-52], the effect of centrally administered ADM[13-52] on renal sympathetic nerve activity (RSNA) was studied. The result showed that centrally administered ADM [13-52] (1.6 nmol/kg) provoked a marked increase in RSNA, therefore, the increases in MABP and HR induced by centrally administered ADM [13-52] might be due to the stimulation of central sympathetic mechanism. In addition, we also compared the relationship of activity and structure among the different fragments of ADM. In conclusion, ADM exists in the rat brain, and it may play an important role in the central control of cardiovascular system.

Adrenomedullin↗
PubMed1996

[Difference of the discharges from the postganglionic fibers of the celiac ganglion induced by electroacupuncture at zusanli and yanglingquan].

The changes of the discharge from postganglionic fibers of the celiac ganglion induced by electroacupuncture (EA) at Zusanli and Yanglingquan were measured on 25 healthy rabbits. The result shows that the sympathetic activity can be inhibited by EA at both acupoints above. The depression of the sympathetic activity resulted from EA at Zusanli was significant stronger than that at Yanglingquan (P < 0.05). This result indicates that there is the relative individuality in the function of the different acupoints on the different channels.

Acupuncture Points↗
PubMed1996

Pharmacokinetics of m-nifedipine in rabbits after intravenous injection.

AIM: To study the dose effects on pharmacokinetics of m-Nif. METHODS: Fifteen rabbits were divided into 3 groups receiving i.v. m-Nif 0.5, 1, and 2 mg.kg-1. Plasma levels of m-Nif were determined with HPLC method. RESULTS: The concentration-time data were fitted with 2-compartment model. After i.v. 1 mg.kg-1, the parameters were: Vd = 0.37 +/- 0.10 L.kg-1, T1/2 alpha = 6.4 +/- 2.9 min, T1/2 beta = 84 +/- 22 min, AUC = 94 +/- 16 mg.min.L-1, Cl = 0.65 +/- 0.13 L.kg-1.h-1. No statistically significant difference was found in Cl and T1/2 beta between 3 dose groups. AUC (standardized to body weight) was correlated with doses. CONCLUSIONS: m-Nif was distributed widely and eliminated at a fairly rapid rate in the rabbits. No dose-dependent pharmacokinetics was found after i.v. m-Nif 0.5-2 mg.kg-1. m-Nifedipine, 2, 6-dimethyl-3, 5-dicarbomethoxy-4-(3'-nitrophenyl)-1, 4-dihydropyridine (m-Nif) is a new calcium channel blocker. Dihydropyridine calcium channel antagonists are mainly used for the treatment of hypertension and angina[1]. Nifedipine is susceptible to photodegradation, but m-Nif is stable when exposed to light. The 2 drugs have the same antihypertensive effect[2]. So far, no report has been found on pharmacokinetics of m-Nif. Using a high performance liquid chromatographic (HPLC) method, we studied the dose effects on the pharmacokinetics of i.v. m-Nif 0.5, 1, and 2 mg.kg-1 in conscious rabbits.

Animals↗
PubMed1995

Purification and characterization of carboxypeptidase D, a novel carboxypeptidase E-like enzyme, from bovine pituitary.

Carboxypeptidase E (CPE) is involved in the biosynthesis of most neuropeptides and peptide hormones. Until recently, CPE was the only intracellular carboxypeptidase thought to be involved in neuroendocrine peptide processing. However, the finding that fat/fat mice, which have a mutation within the CPE gene that inactivates the enzyme, are capable of a reduced amount of insulin processing suggests that another carboxypeptidase is present within the secretory pathway. We have detected a CPE-like enzyme, designated CPD, which has many properties in common with those of CPE. Like CPE, CPD is a metallocarboxypeptidase that has a pH optimum of 5.5-6. The Km and Kcat values for a series of short peptide substrates show only minor differences between CPD and CPE. Several active site-directed inhibitors also show generally similar potency toward the two enzymes, although guanidinoethylmercaptosuccinic acid is approximately 10-fold more potent, and hippuryl-Arg is approximately 100-fold more potent as an inhibitor of CPD than of CPE. A major difference between the two enzymes is the molecular masses; CPE is 50,000-56,000, whereas CPD is approximately 180,000. Also, CPD does not elute from a substrate affinity column when the pH is raised to 8, which elutes CPE, although CPD can subsequently be eluted by arginine. Both CPE and CPD are present in purified bovine anterior pituitary secretory vesicles, but the tissue distribution of CPD is more uniform than that of CPE. Antisera to the N- and C-terminal regions of CPE do not recognize CPD. The partial N-terminal amino acid sequence of bovine CPD shows 30-40% homology with an N-terminal region of bovine and rat CPE and 70% homology with a duck protein known as gp180, a hepatitis B virus particle binding protein that shows 47% homology to CPE. Taken together, these results suggest that CPD is a novel secretory pathway enzyme that may be the bovine homologue of gp180.

Amino Acid Sequence↗
PubMed1995

[Study of subcuticular suture skill for perineotomy and catgut-suture reaction].

The post perineotomy complications such as catgut-suture-reaction, incision infection, and laceration are very common in the hospital. The purpose of this study was to find a better suture skill. The subcuticular suture skill was studied in this study. The relationship between suture skill and catgut suture reaction was analysed. 200 women had vaginal delivery with perineotomy subcuticular suture who were hospitalized during 3 to 10 in 1994 were compared with 399 women with perineotomy routine suture skill who were hospitalized during the same period in 1992 and 1993. The result indicated that the incidence of cat gut suture reaction and secondary suture in the research group were 9%, 7.5% lower than that in control group (P < 0.01). The average time of hospitalization was 5.3 days shorter (P < 0.025). These implicate the future study on perioneotomy suture skill.

Catgut↗
PubMed1995

Calcium- and pH-dependent aggregation of carboxypeptidase E.

Carboxypeptidase E (CPE) is involved with the biosynthesis of numerous peptide hormones and neurotransmitters. Several forms of CPE have been previously detected in neuroendocrine cells, including a form which is soluble at pH 5.5 (S-CPE), a form which can be extracted from membranes with 1 M NaCl at pH 5.5 (M1-CPE), and a form which requires both 1% Triton X-100 and 1 M NaCl for extraction from membranes at pH 5.5 (M2-CPE). Like other peptide processing enzymes, CPE is known to be sorted into peptide-containing secretory vesicles of the regulated pathway. One mechanism that has been proposed to be important for sorting of regulated pathway proteins is Ca2+ and pH-induced aggregation. CPE purified from bovine pituitary membranes aggregates at pH 5.5 when the concentration of CPE is 0.3 micrograms/microliters or higher, but not when the concentration is 0.01 microgram/microliters. Aggregation of CPE is pH-dependent, with very little aggregation occurring at pH 6 or above. At pH 5.0-5.5, the M2 form of CPE shows a greater tendency to aggregate than the other two forms. At pH 6, Ca2+ concentrations from 1-30 mM increase the aggregation of M1- and M2-CPE, but not S-CPE. The aggregation of M2-CPE does not explain the apparent membrane binding of this protein since the aggregate is solubilized by 1% Triton X-100 at pH 5.5 or by pH 6.0, whereas M2-CPE is not extracted from membranes under these conditions. Taken together, these results are consistent with a model in which the decreasing pH and increasing Ca2+ levels in the trans Golgi network induce the aggregation of CPE, which contributes to the sorting of this protein into regulated pathway secretory vesicles.

Amino Acid Sequence↗
PubMed1995

Pelvic and pudendal reflexes in the in vitro neonatal rat preparation.

Pudendal-to-pelvic and pudendal-to-pudendal reflexes are described in an in vitro brainstem-spinal cord neonatal rat preparation. Cystometrograms and peripheral pelvic nerve recordings were used to monitor excitatory micturition reflexes evoked by tactile perineal stimulation or by continuous electrical stimulation of the sensory pudendal nerve. Micturition was characterized by an increased bladder pressure and a period of tonic pelvic nerve activity during which time fluid was expelled from the urethra. Single stimuli delivered to the sensory pudendal nerve evoked a phasic response in the pelvic nerve (pudendal-to-pelvic reflex) or pudendal motor nerve (pudendal-to-pudendal reflexes). The pudendal-to-pelvic reflex consisted of a single response occurring after a mean latency of 98 +/- 24 ms. The pudendal-to-pudendal reflex was comprised of two responses, the first occurred at a mean latency of 105 +/- 11 ms and the second at 383 +/- 36 ms. Cervical or lower thoracic spinal transection did not alter the pudendal-to-pelvic reflex, however, the second component of the pudendal-to-pudendal reflex was abolished. The use of preganglionic pelvic and pudendal peripheral nerve recordings described in this study provide a direct measure of the reflex outflow from the CNS and can be used to examine developmental changes and neurochemical substrates within the CNS which contribute to micturition and coital reflexes in the rat.

Animals↗
PubMed1995

Barriers to social network interventions with persons with severe and persistent mental illness: a survey of mental health case managers.

In order to empirically assess the existence, strength, and relative influence of barriers to social network interventions for persons with severe mental disability which have been cited in the literature, a survey of the knowledge and attitudes of social networks and social network interventions of eighty mental health case managers and case management supervisors was conducted. Findings indicate gaps in case managers' level of knowledge of social networks, with items based on empirical knowledge about social networks and severe mental disability least likely to be answered correctly. Case managers both perceive, and have experienced, a significant number of obstacles that affect their ability to develop social network interventions-system barriers (paperwork, caseload size, lack of case manager time, etc.), community barriers (stigma and lack of resources), and client/family barriers (lack of interest in social networks, clients having a "burnt out" network, clients not wanting to identify social network needs, etc.). Case managers cited few major barriers pertaining to their own level of knowledge, skills, or interest in, social network interventions. Strategies to address identified barriers are presented.

Adult↗
PubMed1995

Photobleaching kinetics of fluorescein in quantitative fluorescence microscopy.

An investigation on the photobleaching behavior of fluorescein in microscopy was carried out through a systematic analysis of photobleaching mechanisms. The individual photochemical reactions of fluorescein were incorporated into a theoretical analysis and mathematical simulation to study the photochemical processes leading to photobleaching of fluorescein in microscopy. The photobleaching behavior of free and bound fluorescein has also been investigated by experimental means. Both the theoretical simulation and experimental data show that photobleaching of fluorescein in microscopy is, in general, not a single-exponential process. The simulation suggests that the non-single-exponential behavior is caused by the oxygen-independent, proximity-induced triplet-triplet or triplet-ground state dye reactions of bound fluorescein in microscopy. The single-exponential process is a special case of photobleaching behavior when the reactions between the triplet dye and molecular oxygen are dominant.

Fluorescein↗
PubMed1995

Processing of procarboxypeptidase E into carboxypeptidase E occurs in secretory vesicles.

Carboxypeptidase E (CPE) functions in the posttranslational processing of bioactive peptides. Like other peptide processing enzymes, CPE is initially produced as a precursor ("proCPE") that undergoes posttranslational processing at a site containing five adjacent Arg residues near the N-terminus and at other sites near the C-terminus of proCPE. The time course of the N-terminal processing step suggests that this conversion occurs in either the Golgi apparatus or the secretory vesicles. To delineate further the site of proCPE processing, pulse/chase analysis was performed under conditions that block transit out of the Golgi apparatus (brefeldin A, carbonyl cyanide m-chlorophenylhydrazone, or 20 degrees C) or that block acidification of vesicles (chloroquine, monensin, or ammonium chloride). The results of these analysis suggest that efficient proCPE processing requires an acidic post-Golgi compartment. To test whether known processing enzymes can perform this cleavage, purified proCPE was incubated with furin, prohormone convertase 1, or a dynorphin converting enzyme, and the products were analyzed on denaturing polyacrylamide gels. Furin cleaves proCPE within the N-terminal region, although the reaction is not very efficient, requiring relatively large amounts of furin or long incubation times. The other two peptide processing enzymes did not cleave proCPE, whereas a relatively small amount of secretory granule extract was able to convert proCPE into CPE. Taken together, these findings suggest that the conversion of proCPE into CPE occurs primarily in secretory vesicles.

Amino Acid Sequence↗