Biomedical subjects

T Fan

Publications and source records attributed to T Fan.

At least 37 records · Page 2Linked to original sources

PubMed1996

Variety of molecular conformation of plasmid pUC18 DNA and solenoidally supercoiled DNA.

The plasmid pUC18 DNA isolated from Escherichia coli HB101 were analyzed by two-dimensional agarose gel electrophoresis and hybridization. The results show that the DNA sample can be separated into six groups of different structural components. The plectonemically and solenoidally supercoiled pUC18 DNA coexist in it. These two different conformations of supercoiled DNA are interchangeable with the circumstances (ionic strength and type, etc.). The amount of solenoidally supercoiled pUC18 DNA in the samples can be changed by treatment of DNA topoisomerases. Under an electron microscope, the solenoidal supercoiling DNA has a round shape with an average diameter of 45 nm. The facts suggest that solenoidally supercoiled DNA be a structural entity independent of histones. The polymorphism of DNA structure may be important to packing of DNA in vivo.

DNA Topoisomerases, Type I↗

PubMed1995

Low endogenous dopamine function in brain predisposes to high alcohol preference and consumption: reversal by increasing synaptic dopamine.

Using inbred strains of mice that differ widely in their innate preference for and consumption of ethanol, we demonstrate, in ethanol-preferring C57BL/6J (C57) mice, decreased dopamine (DA) content and turnover in the terminals of the mesolimbic and mesostriatal dopamine neurons, compared with ethanol-avoiding DBA/2J and BALBc mice. These data suggest that genetically determined hypodopaminergic function in these pathways plays a role in the predisposition to high voluntary intake of ethanol. DA turnover in these areas was selectively increased by ethanol in C57 mice, which suggests that these DA neurons are among the central substrates of ethanol action in brain. In keeping with this hypothesis, augmenting synaptic DA concentrations by enhancing the synthesis by L-3-4-dihydroxyphenylalanine with carbidopa, or by decreasing its degradation by monoamine oxidase-B blockade with selegiline, led to marked decreases in ethanol preference and in the high voluntary consumption of ethanol in C57 mice. The selegiline-mediated decrease in ethanol preference and drinking in C57 mice could be blocked selectively by D1 and D2 DA receptor antagonists, which suggests that DA activity at D1 and D2 receptors plays an important role in this behavior. Indeed, the high preference for ethanol in C57 animals could be attenuated by direct DA receptor activation by either D1 or D2 agonists.(ABSTRACT TRUNCATED AT 250 WORDS)

Alcohol Drinking↗

PubMed1995

[Diagnosis and treatment of interrupted aortic arch: report of 6 cases].

Six patients with interrupted aortic arch were operated on from Nov. 1986 to Jun. 1992. 4 patients were type A and 2 type B. The result was good except a patients of type A died early after operation. Two-stage operation was performed for 4 patients of type A, and 2 patients of type B accepted posterolateral incision. The aortic arch was constructed with artificial vessel. Cardiopulmonary bypass was set up with patients lying on back, then PDA was ligated and VSD closed. Pulmonary artery trunk reconstruction and VSD closing were performed. Three months after operation a patient died of septicemia caused by infection of incision.

Adolescent↗

PubMed1995

[Afferent projections to the central superior raphe nucleus of brain stem and its relation to acupuncture anesthesia].

The afferent projections to the central superior raphe nuclus (CS) in the rat were investigated by means of HRP retrograte tracing method. 3% WGA-HRP 0.05-0.1 microliters was injected into the CS in each of 11 rats. The labeled cells were found in the medial part of lateral habenular nucleus, posterior hypothalamic area, lateral subnucleus of interpeduncular nucleus, dorsal raphe nucleus, periaqueductal gray matter, dorsal paramedial nucleus, preposital hypoglossal nucleus, dorsal paragiganto-cellular nucleus, magnum raphe nucleus, and fastigatum of cerebellum. The results provide morphological basis for researching function of the CS in acupuncture anesthesia.

Acupuncture Analgesia↗

PubMed1994

Evaluation of school children at high risk for fragile X syndrome utilizing buccal cell FMR-1 testing.

We describe a pilot project utilizing saliva to identify the FMR-1 mutation in high-risk special education students from four public school districts in Colorado. The program included presentations to special education teachers regarding fragile X syndrome, parental consent for testing, completion of a behavior checklist by the teachers, identification of special education students at high risk for fragile X syndrome, subsequent brief examination of face and hands, collection of a saliva sample by either Gatorade swish or brushing of the inside of the cheek, and analysis for the FMR-1 mutation by PCR. Equivocal samples were studied by direct DNA testing using Southern blot analysis, and abnormal results were confirmed by a blood analysis for the FMR-1 mutation. Mutant individuals received genetic counseling and medical and educational assessments to optimize treatment and intervention. This pilot project was met with enthusiasm by the schools. Of the first 439 students evaluated, 68% were male with an average age of 7.75 years; 13% were mentally retarded or autistic. Most students referred for the evaluation were learning disabled (51%) and/or had an Attention Deficit Hyperactivity Disorder (ADHD) (35%). The overall prevalence of the FMR-1 mutation was 5 of 439 or 1.1%. This relatively low yield is probably due to the high number of non-retarded but learning disabled students tested. Of the mentally retarded patients tested, 3.5% were positive for the FMR-1 mutation; however, of the non-retarded or learning disabled patients, only 0.79% were FMR-1 positive.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1993

[Relationship between acupuncture analgesia and neurotransmitters in nucleus raphe magnus].

Nucleus Raphe Magnus (NRM) is a complex cell group. 5-HT, SP and ENK neurons in the NRM were identified by immunocytochemistry method. The afferent fibers containing 5-HT, SP, M-ENK, L-ENK, B-EP and SRIF were observed in NRM, the efferent fibers containing 5-HT, SP, ENK and TRH from NRM to spinal cord were studied. Two neurotransmitters (such as 5-HT with SP, ENK or TRH) were found in same neuron, fiber or vesicle. The neurons and axo-dendritic synapses of the NRM were analysed during Electroacupuncture (EA). The NRM increased their synaptic releases and the neurons were in active functional state during EA "Zusnanli". Studies show that NRM is one of important positions in EA analgesia.

Acupuncture Analgesia↗

PubMed1993

[Electroacupuncture promotes the regeneration of different fibers in rat's tibial nerve].

METHODS: 45 rats (150-200g) were divided into 9 groups. The experimental steps as follows: (1) injured left tibial nerve (group 1-8) and sham operation (group 9); (2) three days after operation, group 1, 3, 5 and 7 were stimulated with electro-acupuncture (EA) in Huantiao (+) and Sanyinjiao (-); (3) according to different survival time (group 1, 2/10 days, group 3, 4/15 days, group 5, 6/20 days, group 7, 8, 9/25 days), 48h before sacrifice, the left femoral nerve was cut, HRP was injected into the hypodermis of paw pad and gastrocnemius; (4) observe HRP labelled cells in the lumber sympathetic ganglia, ganglion spinale (L4-6) and cornu ventrale of spinal cord (L3-S3). RESULTS: EA 7 days, 2-5 labeled cells were only found in ganglion spinales of group 1; EA for 12 days, the more HRP labeled cells were observed in the lumber sympathetic ganglions (mean = 2.6), ganglion spinales (mean = 4.8) and cornu ventrale (mean = 6) of group 3 as compared with group 4 (P < 0.05); 25 days after operation, the quantity of labeled cells in group 8 was close to group 9. CONCLUSION: (1) EA promote the regeneration of three or more kinds of fibers in tibial nerve; (2) The regeneration velocity of sensory fibers was faster than sympathetic and somatic efferent fibers.

Animals↗

PubMed1992

[Research on serotonergic neurons in lateral raphe nucleus of rat with intracellular injection HRP technique].

UNLABELLED: This experiment was carried out on 35 rats with stereotaxic apparatus following a new coordinate which was designed by ourselves. The microelectrode was pushed into the lateral dorsal raphe nucleus (LDR) under direct vision. The neurons with regular rhythm and slow firing rate were searched by intracellular recording, then the singular cell in LDR was filled with HRP by intracellular iontophoresis. RESULTS: 7 HRP labelling neurons with serotoninergic firing characteristics were observed in LDR. The labelling dendrites were found in neighboured structure (periaqueductal gray, laterodorsal tegmental nucleus, dorsal tegmental nucleus, 4th ventricle). This work demonstrated that LDR plays some role in acupuncture analgesia.

Action Potentials↗

PubMed1992

[Electron microscopic observation on the effect of electroacupuncture (EA) on the ultrastructure of nucleus raphe dorsalis (NRD) in rats].

Nucleus raphe dorsalis (NRD) plays an important role in acupuncture analgesia. The aim of this investigation is to determine the effects of electroacupuncture (EA) analgesia on the ultrastructure of NRD. 12 Wistar rats (220-250g) were divided into control and experiment groups. Pain threshold was determined by potassium iontophoretic colorimetry. EA was applied at bilateral "Zusanli" points. The effective analgesia animals and control animals were sacrificed and the NRD were taken out for electron microscopic observation. In EA analgesia groups, NRD was observed the number of the clear round vesicle-containing terminals and clear round vesicles with the granular vesicle-containing terminals showed a significant decrease and sometimes vesicles were emptied. The area of presynaptic terminals were expanded. Some synaptic gaps appeared narrow profiles. Part of the mitochondria and endoplasmic reticulum in neuron and neurogliocytes appeared the expanded profiles. These ultrastructural change of the NRD in EA analgesia might indicate the neurons and neurogliocytes were in active functional state.

Acupuncture Analgesia↗

PubMed1991

[Studies on the relationship between acupuncture analgesia and testosterone or dihydrotestosterone in blood plasma].

UNLABELLED: 55 rats (Wistar, Male, 250-350 g) were divided into 4 groups: (1) BTA (bilateral testectomy + adrenalectomy) group, (2) BT (bilateral testectomy) group, (3) BA (bilateral adrenalectomy) group, (4) SO (sham operation) group. EA was applied to bilateral "Tsusanli" points of each animal at 72 h. after operation. The potassium iontophoretic colorimetry was used to determine the pain threshold of rats, radioimmunoassay was used to measure the contents of T and DHT in femoral vein blood. T, DHT and the pain threshold of each animal were measured before operation, at 72 h, after operation and after EA, but for the SO group the measurement was done once at 72 h. after im testosterone phenylacetate. RESULTS: The content of T in BTA and BT groups were decreased. significantly at 72 h. after operation, but the changes of the pain threshold were similar to BA and SO groups. After EA the content of T in BT and SO groups were raised significantly (P less than 0.01), but in BT group raised slightly (P greater than 0.05). It was found in all animals that the content of DHT and the pain threshold were significantly elevated at 45 min after EA. No effect upon the pain threshold and EA analgesia was observed in SO group after im testosterone phenylacetate. CONCLUSION: T (from testes and adrenal) and DHT rose markedly after EA. Increasing T and DHT or decreasing T in plasma had no effect upon the pain threshold and EA analgesia. It is suggested that T and DHT in plasma may not play a role in the EA analgesia, in the other hand, EA may be used for improving the hypogonadal condition.

Acupuncture Analgesia↗

PubMed1990

Corticotropin-releasing factor is altered in brains of animals with high preference for ethanol.

Ethanol administered to rats has been shown to stimulate the hypothalamic-pituitary-adrenal axis. The present study describes alterations in brain CRF neuronal systems that accompanied the voluntary high consumption of ethanol by Wistar rats presented with a free choice between 6% ethanol and tap water. Hypothalamic CRF concentrations (outside median eminence) were significantly increased in animals with a high preference for ethanol whereas concentrations of CRF in neurointermediate pituitary and medulla-pons were significantly decreased. No changes of CRF levels were evident in median eminence, frontal cortex, midbrain, thalamus, or cerebellum. Brain CRF concentrations in two strains of mice with genetically determined differential alcohol preference were measured. In ethanol-naive mice, there were documented differences in CRF concentrations, with an increase in frontal cortex levels, and a decrease in medulla-pons levels in the ethanol-preferring strain (C57BL/6J) compared to the nonpreferring strain (C3H/CRGL/2). Thus, certain brain CRF neuronal systems are preferentially affected by high ethanol consumption, and pre-existing differences in these systems may even contribute to the development of a high preference for ethanol.

Alcohol Drinking↗

PubMed1990

[Electron microscopic observation on the effect of electroacupuncture (EA) on the ultrastructure of periaqueductal gray (PAG) and nucleus raphe magnus (NRM) in rats].

12 Wistar rats (220-250g) were divided into control and experimental groups. Pain threshold was determined by WQ-9E Pain Threshold Measuring Apparatus. EA was applied at bilateral "Zusanli" points. The animals showing EA analgesia and the control animals were sacrificed and the ventrolateral part of PAG and the NRM were taken out for electron microscopic observation. The peripheral region of ventrolateral PAG (PAG-PR) and the NRM contained a wide variety of cell types and synaptic relationships. The neurons and axo-dendritic synapses of the PAG-PR and NRM were analysed in EA and control groups. In EA analgesia group, the clear round vesicle-containing presynaptic boutons and the presynaptic bouton with clear round vesicles and granular vesicles showed a significant decrease of their vesicle content. Part of the mitochondria and endoplasmic reticulum in the neurons appeared the expanded profiles. These ultrastructural changes of the PAG and the NRM during EA analgesia may indicate an increased release of acetylcholine, biogenic amines and/or peptide neurotransmitters and that the neurons were in active functional state.

Acupuncture Analgesia↗

PubMed1989

31P spectroscopy in thrombolytic treatment of experimental cerebral infarct.

Ischemic changes produced by autogenous clot embolization of intracranial arteries were monitored by continuous surface-coil 31P spectroscopy in 12 rabbits: six were used as controls and six were treated intravenously with tissue-type plasminogen activator. The animals were sacrificed and the brains were fixed with intravital stains. The results indicate that spectral changes are reversible only when thrombolysis therapy is started within 30 min after ischemic changes are detected. The improvement of the 31P spectrum correlated with postmortem changes.

Animals↗

PubMed1989

[New cloning vectors constructed in Bacillus].

Two new plasmids pNQ216 (4.1kp) and pNQ402 (2.8 kb) were constructed by combining the replication origin of the plasmid pNK289, a cryptic plasmid resides in B. pumilus 289, and the cat-86 gene from plasmid pPL601. These two plasmids can be maintained steadily in both B. subtilis and B. pumilus. The penetrance of these plasmids on LB medium with Cm (20 micrograms/ml) is 30% higher than that of pPL600. Thus both of these plasmids can be used as new cloning vectors in Bacillus.

Bacillus↗

PubMed1987

Microbore HPLC/mass spectrometry for the analysis of peptide mixtures using a continuous flow interface.

Microbore HPLC techniques have been combined with fast atom bombardment mass spectrometry to provide HPLC/MS capabilities for the analysis of mixtures of peptides and small proteins. The interface between the liquid chromatograph and mass spectrometer is a continuous flow direct insertion probe which contains a fused silica capillary that delivers the eluting solvent to the FAB source of the mass spectrometer at a rate of 5-10 microL/min. Data are presented for the analysis of several mixtures of peptides ranging in molecular weights from about 900 to 6000 daltons. In addition, the analysis of 100 pmol of a tryptic digest of whale myoglobin is shown where 16 of the possible 19 peptides were identified in the mass range m/z 2200-250. The advantages of this approach to HPLC/MS are a relatively high sensitivity because of the low flow rates and low background, and the ability to detect high molecular weight compounds.

Animals↗

PubMed1987

Increase in the brain regional depolarization-dependent Ca2+ uptake in rats preferring ethanol.

The depolarization-dependent Ca2+ uptake system has been suggested to be involved in the release of transmitter and synaptic facilitation. It can be employed as an effective probe to study neurotransmission. Although ethanol has been shown to inhibit or facilitate neurotransmission very little is known about the intrinsic activity of neurotransmission in ethanol-preferring rats. Using the depolarization-dependent Ca2+ uptake system, we demonstrated that synaptic neurotransmission is more active in animals with moderate and high preference for ethanol. Results suggest that there are intrinsic differences in the brain regional neurotransmission among rats showing different degrees of preference for ethanol.

Alcohol Drinking↗

PubMed1986

High sensitivity mass spectrometric determination of peptides: direct analysis of aqueous solutions.

The high sensitivity analysis of peptides by fast atom bombardment mass spectrometry has been achieved using a continuous flow probe for the introduction of samples contained in aqueous solutions. Small aliquots of sample (0.5-1 microliter) are injected into a solvent flow containing water/glycerol (8:2). For several peptide samples tested whose molecular weights were between 1000 and 1500 daltons, molecular ions were selectively monitored at the 20 fmol level with a signal-to-chemical noise of about 4:1, and full scan data were obtained on about 5 pmol of sample. The increase in sensitivity observed using the continuous flow probe is shown to be a consequence of both the decrease in the chemical background noise and to the increase in ion yields obtained from the bombardment of aqueous sample solutions.

Mass Spectrometry↗

PubMed1986

Peptide sequence analysis using exopeptidases with molecular analysis of the truncated polypeptides by mass spectrometry.

Fast atom bombardment mass spectrometry is used for the analysis of the series of molecular products formed by the cleavage of polypeptide substrates with the exopeptidases carboxypeptidase Y and leucine aminopeptidase. By following the polypeptide molecular species rather than the released residues, sequence information is obtained regardless of the relative rates of cleavage of peptide bonds. In addition, unambiguous assignments of sequence can be made in the presence of multiple identical residues. The lower level of sensitivity for the analysis is in the picomole range. When carboxypeptidase Y is used, the method provides a specific and sensitive method for the sequencing of polypeptides from the C-terminus.

Amino Acid Sequence↗