Biomedical subjects

L Luo

Publications and source records attributed to L Luo.

At least 199 records · Page 11Linked to original sources

PubMed1996

Psychological long-term effects of sterilization on anxiety and depression.

Two-thousand cases (500 women and 500 men with sterilization; 500 women and 500 men without sterilization) in two counties and two cities in Sichuan, China, were investigated between 15 September 1992 and 30 April 1993. Information was obtained about their age, parity, marriage, contraceptives, social behavior, and present psychological characteristics. CES-D, SAS, and E.P.Q. scales were used to assess the depressive symptomatology, anxiety, and personality of the subjects. The results revealed that sterilization psychologically affected the depressive symptoms and anxiety under the neutral personality. In addition, depressive symptoms and anxiety were related to the subjects' age, educational level, income, operative doctors' attitudes to sterilization acceptors, and subjects' understanding of the sterilization.

Adult↗

PubMed1996

Differential effects of pre-treatment with intrathecal or intravenous morphine on the prevention of spinal cord hyperexcitability following sciatic nerve section in the rat.

The effect of intrathecal (i.t.) and intravenous (i.v.) morphine on spinal hyperexcitability following unilateral section of the sciatic nerve was studied in decerebrate, spinalized, unanesthetized rats. Sciatic nerve section evoked a biphasic, prolonged hyperexcitability of the flexor reflex. Either i.v. (0.2, 1 or 10 mg center dot kg-1) or i.t. (3 or 10 mu g) morphine was administered prior to sciatic nerve section. All doses of morphine significantly depressed the baseline flexor reflex and abolished the less intense prolonged second component of reflex hyperexcitability. One and 10, but not 0.2, mg center dot kg-1 i.v. morphine significantly depressed the first phase of spinal cord sensitization. However, both 3 mu g and 10 mu g i.t. morphine were significantly more effective than i.v. morphine in suppressing spinal cord hyperexcitability. The present results suggest that moderate doses of i.t. morphine decrease spinal hyperexcitability following nerve transection more than even extremely large i.v. doses. The poorer effect of i.v. morphine on preventing spinal hyperexcitability may be due to low spinal concentration after systemic administration.

Analgesics, Opioid↗

PubMed1996

Exon-scanning mutation analysis of the ATM gene in patients with ataxia-telangiectasia.

Using a polymerase chain reaction single strand conformation polymorphism (PCR-SSCP) assay, which amplifies individually all coding exons of the ATM gene deficient ataxia-telangiectasia (A-T), we have analyzed 10 patients with A-T for ATM mutations. Mutation were detected in 9 patients. We describe the first ATM mutation in the splice junction found in the 5' splice site of intron 17, leading to exon skipping. However, most mutations were small deletions or insertions resulting in premature termination of the translation product. The development of DNA-based methods for detection of unknown mutations and further characterization of ATM mutation pattern will facilitate identification of A-T carriers and assessment of their cancer risk.

Ataxia Telangiectasia↗

PubMed1996

A follow-up study of first trimester induced abortions at hospitals and family planning clinics in Sichuan province, China.

Four-thousand women aged 18-40 underwent an early induced abortion at hospitals and family planning clinics in six counties in Sichuan province, China, between 1 July 1990 and 30 June 1991. The subjects were followed-up three times, on days 15, 90 and 180 after the operation. Information was obtained about their age, parity, contraceptive use, social behaviors, and gynecological and psychological characteristics before and after the abortion. The results indicate that induced abortion is safe when provided by medically trained personnel in health facilities such as hospitals or clinics. Depressive symptomatology was assessed by the CES-D and SCL-90 scales. The depressive symptoms declined over time. A substantial proportion of the abortions were to unmarried women or resulted from non-use of contraception or contraceptive failure, implying that the incidence of unintended pregnancies and induced abortions could be reduced by more effective and accessible contraception.

Abortion, Induced↗

PubMed1996

Effects of enflurane and isoflurane anesthesia on the pharmacokinetics of pancuronium in adult patients.

OBJECTIVE: To evaluate the effects of 1 MAC of enflurane or isoflurane anesthesia on the pharmacokinetics of pancuronium. METHODS: Eighteen adult patients undergoing the elective plastic surgery were randomly divided equally into 3 groups, namely, Group 1 (control group), Group 2 (enflurane group) and Group 3 (isoflurane group). Anesthesia was maintained with thiopental and 67% N2O-O2 in Group 1, 1 MAC enflurane in Group 2 and 1 MAC isoflurane in Group 3. After administration of a bolus of pancuronium 100 micrograms/kg, an improved fluorimetric assay was used to determine the serum concentrations of pancuronium and the pharmacokinetic variables of pancuronium were calculated with a 3P87 program. RESULTS: The disposition of pancuronium may be well described mathematically by a two-compartment open model. The results showed that in comparison with the control group, patients in Group 2 and Group 3 had a longer T1/2 beta and MRT. The patients in Group 2 had the slower K10 and lower CL than those in the control group. There were no significant differences among the three groups in T1/2 alpha, V1, V2, Vdss, V beta, K21, K12 and AUC. CONCLUSION: During enflurane and isoflurane anesthesia, CL of pancuronium decreased, and T1/2 beta and MRT of pancuronium were prolonged in our patients, so duration of the effective plasma concentrations of pancuronium was much longer. As a result, the effects of enflurane and isoflurane of the pharmacokinetics of pancuronium may be part of reason why two drugs extended the duration of neuromuscular depression produced by pancuronium.

Adolescent↗

PubMed1996

Small GTPases in axon outgrowth.

We propose that small GTPases in the Rho/Rac/Cdc42 subfamily play a central role in signaling pathways from cell surface receptors to actin cytoskeleton changes in the growth cone. The proposal is based upon the following evidence. First, the Rho/Rac/Cdc42 subfamily GTPases have been shown to regulate various aspects of cytoskeletal organization from budding yeast to mammalian fibroblasts. Second, perturbation of GTPase activities of Rac and Cdc42 in neurons by constitutively active and dominant negative mutants results in specific defects in axon and dendrite outgrowth. In addition to reviewing existing experimental evidence, we will discuss the implications of such a model and the potential relationship with other signaling pathways.

Animals↗

PubMed1996

[The pharmacokinetics of pancuronium bromide in infants, children and adults].

Twenty-four patients scheduled for elective plastic surgery were selected to study the pharmacokinetics of pancuronium bromide under enflurane anesthesia. The patients were divided into three groups by their ages; Group 1 consisted of 5 infants (0.75-2.95 years); Group 2 contained 13 children (4-14 years); Group 3 included 6 adults (16-27 years). An improved fluorimetric assay was used to measure the plasma concentrations of pancuronium bromide after administration of pancuronium bromide at a dose of 100 micrograms/kg. The results showed that the disposition of pancuronium bromide may be best described mathematically by a two-compartment open model in all patients. The younger the patients, the larger the distribution volumes and the higher the Cl. There were significant differences among the three groups with regard to V1, V2, Vdss, Cl, AUC. The T1/2 beta and MRT were longer in Group 1 than in Group 2 and Group 3.

Adolescent↗

PubMed1996

Effect of hypoxia on DNA synthesis and c-myc gene expression of pulmonary artery smooth muscle cells.

The neonate is particularly susceptible to the development of hypoxic pulmonary hypertension. The present study was undertaken to observe the effect of hypoxia on DNA synthesis and c-myc gene expression between newborn calf and adult bovine PASMC in vitro. DNA synthesis measured by 3H-TdR incorporation was increased after hypoxic challenge for 24h. Hypoxia enhanced the increment in 3H-TdR incorporation induced by EGF. Northern blot analysis revealed that PASMC cultured in both normoxia and hypoxia expressed c-myc gene transcript of 2.2Kb, but there is a higher 2. 2Kb mRNA expression in hypoxic PASMC than that in normoxia. We speculate that newborn calf PASMC exhibited potential response to hypoxia than adult, which was augmented by EGF. Enhanced c-myc gene expression may lead to a great understanding of the mechanism of PASMC growth in the development of pulmonary hypertension.

Animals↗

PubMed1996

Increased expression of PDGF and c-myc genes in lungs and pulmonary arteries of pulmonary hypertensive rats induced by hypoxia.

The role of growth factors and proto-oncogene in pulmonary vascular structural remodelling is not well known. The present study examined gene expression of platelet-derived growth factor (PDGF)-A and -B chain and proto-oncogene, c-myc, in lung tissue and pulmonary artery of rats exposed to hypoxia and compared to those levels of gene expression in normal rats. Normal lungs and pulmonary artery expressed PDGF-A chain transcript of 1.7 kb and PDGF-B chain transcript of 3.5 Kb. The c-myc transcript of 2.2 kb was expressed as well. After hypoxic exposure for 7 and 14 days mRNA levels of PDGF-B chain and c-myc were elevated significantly compared with those of control rats. PDGF-A chain mRNA increased after hypoxia for 7 days, and then declined. These results suggest that activation of autocrine and/or paracrine is important in proliferation mechanism of pulmonary artery smooth muscle cells in hypoxic pulmonary hypertensive rats.

Animals↗

PubMed1996

[Expression of retroviral transmembrane envelope protein p15E in human malignant cells].

Malignant tumor growth is always accompanied with immune suppression. Tumor-derived immuno-suppressive factors, among others, are thought to be responsible, but their nature is not well defined. The paper reports on the expression of an immuno-suppressive retroviral transmembrane envelope protein p15E at different levels in human cancer cells. By using immunohistochemistry, enzyme-linked immunosorbent assay, flow cytometry and in situ hybridization, p15E expression could be demonstrated in cancers of the esophagus, nosopharynx, rectum, ovary (including malignant effusion and cell lines), stomach and breast. Enhanced expression of p15E was also observed in activated lymphocytes of cancer patients as shown by RT-PCR technique. The results indicate that p15E of tumor origin, and perhaps that from activated lymphocytes, may contribute to the immune suppression associated with malignancy.

Gene Products, gag↗

PubMed1995

Structural and electronic similarity but functional difference in methylmalonyl-CoA mutase between coenzyme B12 and the analog 2',5'-dideoxyadenosylcobalamin.

The cofactor analog 2',5'-dideoxyadenosylcobalamin (ddAdoCbl) differs from the natural cofactor coenzyme B12 [5'-deoxyadenosylcobalamin (dAdoCbl)] by lacking only one oxygen atom. The 1H and 13C NMR spectra of ddAdoCbl have been assigned unambiguously by homonuclear and heteronuclear 2D NMR techniques. The 1H, 13C, and 31P chemical shift values for ddAdoCbl were compared with those of another organocobalamin, namely dAdoCbl. This assessment shows that the analog is very similar both electronically and structurally to the natural cofactor. The effectiveness of ddAdoCbl as a cofactor for both the human and Propionibacterium shermanii methylmalonyl-CoA mutases was compared with that of the natural cofactor. ddAdoCbl was found to be a competitive inhibitor with respect to dAdoCbl. Similar binding affinities to both enzymes were found for both the ddAdoCbl analog and the natural cofactor. However, in the presence of ddAdoCbl, the rate of conversion of methylmalonyl-CoA to succinyl-CoA was only 1-2% of that seen with the natural cofactor. There were no changes with time in the visible absorption spectrum of the bound cofactor analog in the presence of substrate, suggesting that the Co-C bond was not cleaved. The CD (circular dichroism) spectra of dAdoCbl and ddAdoCbl are very similar, consistent with the NMR results. The CD spectral changes upon binding to P. shermanii methylmalonyl-CoA mutase are large compared to those reported on the binding of dAdoCbl to ethanolamine ammonia lyase. Furthermore, the CD spectra of both enzyme-bound cobalamins are very similar, suggesting that similar changes in the conformation or structure in these cobalamins occur on binding to the enzyme.(ABSTRACT TRUNCATED AT 250 WORDS)

Circular Dichroism↗

PubMed1995

Distribution of non-NMDA glutamate receptor mRNAs in the developing rat cochlea.

In situ hybridization was used to document the distribution of mRNA encoding six subunit isoforms of non-N-methyl D-aspartic acid (NMDA) glutamate receptors (GluR1, GluR2, GluR3, GluR4, GluR5 and GluR6) in the inner ears of embryonic, postnatal and adult rats. GluR2 and GluR3 expression in the spiral ganglion appeared well before birth, and reached adult levels several days before the onset of function in the cochlea. In the spiral limbus, expression of GluR2 and GluR3 mRNA reached very high levels at around the time of birth, then declined after a few days. Low levels of GluR1, GluR4 and GluR6 expression were detected in various tissues of the cochlea during development. In the adult cochlea, GluR expression was limited to GluR2 and GluR3 mRNAs in the spiral ganglion neurons and GluR2 mRNA in fibrocytes of the spiral limbus, a non-neural tissue. The ontogenetic expression of additional GluR subunit genes and their appearance in different cochlear tissues could reflect different roles for these genes during development, or less precise regulation of gene expression within the GluR family. In particular, the very high levels of GluR gene expression in the spiral limbus during the perinatal period support a non-neural function, perhaps as cell surface receptors during tissue differentiation.

Animals↗

PubMed1995

Disassembly of the Mu transposase tetramer by the ClpX chaperone.

Mu transposition is promoted by an extremely stable complex containing a tetramer of the transposase (MuA) bound to the recombining DNA. Here we purify the Escherichia coli ClpX protein, a member of a family of multimeric ATPases present in prokaryotes and eukaryotes (the Clp family), on the basis of its ability to remove the transposase from the DNA after recombination. Previously, ClpX has been shown to function with the ClpP peptidase in protein turnover. However, neither ClpP nor any other protease is required for disassembly of the transposase. The released MuA is not modified extensively, degraded, or irreversibly denatured, and is able to perform another round of recombination in vitro. We conclude that ClpX catalyzes the ATP-dependent release of MuA by promoting a transient conformational change in the protein and, therefore, can be considered a molecular chaperone. ClpX is important at the transition between the recombination and DNA replication steps of transposition in vitro; this function probably corresponds to the essential contribution of ClpX for Mu growth. Deletion analysis reveals that the sequence at the carboxyl terminus of MuA is important for disassembly by ClpX and can target MuA for degradation by ClpXP in vitro. These data contribute to the emerging picture that members of the Clp family are chaperones specifically suited for disaggregating proteins and are able to function with or without a collaborating protease.

ATPases Associated with Diverse Cellular Activitie↗

PubMed1995

Expression of acidic FGF mRNA in rat auditory brainstem during postnatal maturation.

In situ hybridization was used to investigate the mRNA distribution of acidic and basic fibroblast growth factor (aFGF and bFGF) in the auditory brainstem of neonatal and adult rats. bFGF mRNA was not detected at any age. In adult rats, aFGF mRNA was strongly expressed in the principal neurons of the anteroventral and posteroventral cochlear nuclei, but not in the octopus cells. In the dorsal cochlear nucleus, aFGF mRNA was seen only in scattered smaller vertical cells. aFGF was strongly expressed in the nucleus of the trapezoid body and in all periolivary cell groups, but not in the medial and lateral olivary nuclei. No expression was observed in the lemniscal nuclei or in the central nucleus of the inferior colliculus, but large neurons in the external zone of the colliculus were labeled. Developmentally, low levels of aFGF expression appeared in the cochlear nuclei and olivary nuclei between P0 and P6. This expression increased rapidly during the onset of hearing, between P10 and P14, and reached adult level by P14-P17. Labeling in collicular neurons appeared slightly later. The results suggest that the appearance of strong aFGF mRNA expression is related to the onset of function.

Aging↗

PubMed1995

The maximum information principle and the evolution of nucleotide sequences.

The probability distributions of bases in nucleotide sequences are deduced from the maximum information principle by maximizing the entropy (due to random mutation of bases) under certain constraints (Markovian entropy, G + C content, etc, due to selection). Two formulations are given with respect to different selective constraints. The deviations of theoretical distributions from experimental data are lower than 10% for most sequences. It is shown that the Lagrange multipliers change from species to species systematically--i.e. selective constraints correlate with evolution.

Animals↗

PubMed1995

Fuzzy classification of nucleotide sequences and bacterial evolution.

A new method for reconstructing evolutionary relationship among bacteria by use of rRNA sequence data is proposed. The method is based on the concept of fuzzy classification of probabilities p(i), p(i/j) and p(i/j*) (i = A, G, C, U) of each sequence. The resulting partition tree shares common features of previous works but has some new peculiarities.

Animals↗

PubMed1995

Induced abortion among unmarried women in Sichuan province, China.

This report describes the social and demographic characteristics of 457 unmarried women who underwent a first trimester induced abortion at hospitals and family planning clinics in Sichuan province, China. The data show a very low level of medical complications. However, improved access to contraception for unmarried women is needed in order to reduce the incidence of unintended pregnancies and induced abortion.

Abortion, Induced↗

PubMed1995

The effects of pretreatment with tachykinin antagonists and galanin on the development of spinal cord hyperexcitability following sciatic nerve section in the rat.

The effects of acute section of the sciatic nerve on the excitability of the flexor reflex was examined in decerebrate, spinalized, unanaesthetized rats. In control experiments without drugs, the excitability of the flexor reflex was dramatically increased in two phases following axotomy. An early intense, brief reflex hyperexcitability was followed by a less intense, prolonged period of facilitation. The selective NK1 tachykinin receptor antagonist CP-96,345 injected intrathecally at lower (1.2-2.4 nmol) and higher (12 nmol) doses blocked both components of spinal sensitization. The selective NK2 tachykinin receptor antagonist Men 10376 at a dose of 2.4 nmol also reduced both response components, as did the same dose of the inhibitory neuropeptide galanin. Thus, antagonists of excitatory neuropeptides released during and after nerve section, such as substance P and neurokinin A, can block the spinal response to peripheral nerve injury. Furthermore, the inhibitory neuropeptide galanin also reduced spinal cord sensitization.

Afferent Pathways↗