Biomedical subjects

L Nie

Publications and source records attributed to L Nie.

62 records · Page 4Linked to original sources

PubMed1995

In vitro elution of ofloxacin from a bioabsorbable polymer.

A drawback with antibiotic-loaded polymethylmethacrylate (PMMA) beads is the second surgical procedure that may be required to remove the beads. We explored alternatives for the local delivery of antimicrobials and studied the release characteristics of ofloxacin (10 mg) when incorporated into either 30 or 50 mg beads of two different molar ratios of a bioabsorbable lactide: glycolide polymer. An elution method was employed over a 60-day period at 37 degrees C. After 60 days, about half of the ofloxacin had been released from the composites containing 50 mg and 30 mg of the 85:15 polymer, whereas nearly all of the ofloxacin had been released from both sizes of the 50:50 polymer composites.

Biodegradation, Environmental↗

PubMed1995

[Morphine blocked the exitatory amino acid mediated membrane current in ambigual motoneurons of the rat].

Excitatory postsynaptic potentials (EPSPs) and responses of neurons in the compact formation of the neucleus ambiguus (AMBc) to pressure-ejected or bath-applied test substances were recorded intracellularly from sagittal slices of Sprague-Dawley rat medulla containing subnucleus centralis of solitary complex (NTSc), AMBc and solitarioambigual pathway. In 5 cells, recorded spontaneous EPSPs could be blocked by morphine (3-5 pmol) to AMBc. Electrical stimulation of NTSc evoked EPSPs in AMBc neurons, the amplitude of which were decreased to 71.1 +/- 6.2% (P < 0.001) with the addition to morphine. The morphine effect could be abolished by bath-applied naloxone (50 nmol/L). The amplitude of membrane depolarization induced by pressure-ejected N-methyl-D-aspartate (NMDA, 0.5-1.0 pmol), acetylcholine (3 pmol) and quisqualate (0.1-0.5 pmol) to NTSc could also be decreased by bath-applied morphine (10 mumol/L) respectively to 38.1 +/- 5.7% (P < 0.001), 32.8 +/- 5.5% (P < 0.01) and 29.6 +/- 7.1% (P < 0.05). The above results suggest that morphine is capable of block by NMDA, ACh and non-NMDA receptors, increaseing the M-current and decreasing the permeability of Na+ and Ca2+.

Animals↗

PubMed1995

[A cytogenetic study of four species of turtle from China].

The karyotypes, C-banding and Ag-NORs of four species of turtle from China have been studied. The results demonstrated that Cuora aurocapitata has 2n = 52(14M + 2SM + 4ST + 6T / 26m), NF = 72, 8 + 5 + 13(karyotypic formulae). Its secondary constrictions (SC) located on No. 1 p inter of group I; C. trifasciata has 2n = 52(12M + 4SM + 4ST + 6T + 26m), NF = 72, 8 + 5 + 13; Cistoclemmys flavomarginatus has 2n = 52(16M + 4ST + 6T + 26m), NF = 72, 8 + 5 + 13. The SC is also on No. 1 p inter of group I; C. galbinifrons has 2n = 52(16M + 2SM + 4ST + 6T + 24m), NF = 74, 9 + 5 + 12. Four pairs of SC of C. galbinifrons are on No. 1 p inter, No. 3,7 p par and No. 6(X chromosome) q per of group I. The heteromorphic chromosomes related with sexuelity were discovered in C. galbinifrons, while there is no that in other three species. All the centrometric regions of the chromosomes for the four studied species showed the various degree staining of C-positive. Only one homologous pair of Ag-NOR, is found for C. galbinifrons, which locate on No. 5 q per of group II. The Ag-NOR, of other three species lies in No. 7 q ter of group I. The mechanism of the karyotypic evolution is discussed. Individual evolutional mechanism of an heteromorphic sex pair of chromosomes.

Animals↗

PubMed1993

Exclusion of linkage between schizophrenia and the D2 dopamine receptor gene region of chromosome 11q in 112 Irish multiplex families.

A leading theory hypothesizes that schizophrenia arises from dysregulation of the dopamine system in certain brain regions. As this dysregulation could arise from abnormal expression of D2 dopamine receptors, the D2 receptor gene (DRD2) on chromosome 11q is a candidate locus for schizophrenia. We tested whether allelic variation at DRD2 and five surrounding loci cosegregated with schizophrenia in 112 small- to moderate-size Irish families containing two or more members affected with schizophrenia or schizoaffective disorder, defined by DSM-III-R. Evidence of linkage was assessed using varying definitions of illness and modes of transmission. Assuming genetic homogeneity, linkage between schizophrenia and large regions of 11q around DRD2 could be strongly excluded. Assuming genetic heterogeneity, variation at the DRD2 locus could be rejected as a major risk factor for schizophrenia in more than 50% of these families for all models tested and in as few as 25% of the families for certain models. The DRD2 linkage in fewer than 25% of these families could not be excluded under any of the models tested. Our results suggest that the major component of genetic susceptibility to schizophrenia is not due to allelic variation at the DRD2 locus or other genes in the surrounding chromosomal region.

Alleles↗

PubMed1993

[The responses of phrenic discharges to microinjection of morphine and naloxone into central nucleus amygdala in rabbits].

Experiments were done on 24 urethan anesthetized (20%, 1 g/kg), vagotomized and spontaneously breathing rabbits (2-3 kg). The effects on phrenic activity by microinjection of morphine and naloxone into central nucleus amygdala (ACE) were observed. The main results were as follows: (1) Injection of morphine resulted in two respiratory effects, firstly a marked increase in inspiratory time (Ti) and amplitude of phrenic activity (AMP) with little changes of respiratory frequency (RF), and secondly a significant decrease in AMP with little changes in Ti. (2) Injection of naloxone resulted in increases in RF, AMP and decreases in Ti with no marked changes in blood pressure. (3) Prolongation of inspiratory time by morphine can be blocked by previous injection of naloxone. The results suggested that endogenous morphine in ACE have different effects on respiration mediated by different receptor.

Amygdala↗

PubMed1992

Molecular characterization of a 17q11.2 translocation in a malignant schwannoma cell line.

Malignant schwannomas are soft-tissue neoplasms that occur at increased frequency with germline alterations of the neurofibromatosis-1 (NF1) gene at 17q11.2. We report molecular and cytogenetic characterization of a malignant schwannoma cell line established from an individual affected with NF1. This cell line has a complex hyperdiploid karyotype with two cytogenetically identical der(13)t(13;17)(p11,q11.2) chromosomes. Using somatic cell hybrids, we mapped twelve chromosome-17 probes to either the der(13)t(13;17) chromosome or a small der(17) chromosome. Two chromosome-17p loci, including the p53 tumor suppressor gene, were present in the schwannoma cell line, but did not map to either of these chromosomes. Loss of heterozygosity studies indicated that the two der(13)t(13;17) chromosomes arose by duplication, presumably after the translocation event. The 17q11.2 translocation break-point maps distal to the NF1 gene, and may not disrupt its functioning. Although NF1 mRNA was detected in this cell line by polymerase chain reaction, Northern blot analysis revealed very little or none of the 13-kb mature NF1 transcript. This suggests that the single remaining allele of the NF1 gene contains a mutation that results in either greatly reduced transcription or message instability.

Adult↗

PubMed1992

Application of automated DNA sizing technology for genotyping microsatellite loci.

Highly polymorphic microsatellite loci offer great promise for gene mapping studies, but fulfillment of this potential will require substantial improvements in methods for accurate and efficient genotyping. Here, we report a genotyping method based on fluorescently labeled PCR primers and size characterization of PCR products using an automated DNA fragment analyzer. We capitalize on the availability of three distinct fluorescent dyes to label uniquely loci that overlap in size, and this innovation increases by threefold the number of loci that can be analyzed simultaneously. We label size standards with a fourth dye and combine these with the microsatellite PCR products in each gel lane. Computer programs provide very rapid and accurate sizing of microsatellite alleles and efficient data management. In addition, fluorescence signals are linear over a much greater range of intensity than conventional autoradiography. This facilitates multiplexing of loci (since signal intensities often vary greatly) and helps distinguish major peaks from artifacts, thereby improving genotyping accuracy.

DNA, Satellite↗

PubMed1992

[The respiratory facilitating effects by electrical and chemical stimulation of central nucleus amygdala].

Experiments were performed on fifty urethan anesthetized (1 g/kg) rabbits of both sexes, vagotomized and spontaneously breathing. The respiratory responses to electrical and chemical stimulation of ACE were observed. The results were as follows: 1. Long train electrical stimulation of ACE caused significant respiratory facilitating effects: inspiratory prolongation and increase of respiratory rate and depth. 2. Short brust of electrical stimulation administered in ACE during the mid inspiratory and expiratory phases elicited the prolongation of inspiratory phase and the expiratory off-switch (EO-S) effect, respectively. 3. Microinjection of monosodium L-glutamate (MSG) (1 mol/L, 1 microliter) into ACE produced the similar respiratory effects as that of electrical stimulation. 4. Control experiments had no significant effect on respiration. The results showed that the activation of neurons in ACE caused facilitation of respiration. It is suggested that ACE region may take an important part in facilitating the basic respiratory rhythm.

Amygdala↗