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Biomedical subjects

Y H Sun

Publications and source records attributed to Y H Sun.

At least 55 records · Page 3Linked to original sources
PubMed1993

Increased release of immunoreactive CCK-8 by electroacupuncture and enhancement of electroacupuncture analgesia by CCK-B antagonist in rat spinal cord.

Cholecystokinin octapeptide (CCK-8) in CNS has been shown to function as a neuropeptide with potent anti-opioid activity. It hinders opioid analgesia and facilitates opioid tolerance. The present study showed that electroacupuncture (EA) stimulation produced a marked increase of the CCK-8 immunoreactivity (ir) in the perfusate of the rat spinal cord. The increase of CCK-8-ir was most marked in response to EA of 100 Hz and 15 Hz, and less marked in response to EA of 2 Hz. Since CCK-8 has been shown to possess potent anti-opioid activity at the spinal level, blockade of the spinal CCK effect would be expected to potentiate EA-induced analgesia which is known to be opioid-mediated. Intrathecal (i.t.) administration of CCK-B antagonist L-365,260 per se did not affect tail flick latency (TFL) to any significant extent, yet it potentiated EA induced analgesia in a dose- and frequency-dependent manner. The potentiation was most marked at a dose range of 2.5-5.0 ng (i.t.) and at a frequency rank order of 100 Hz > 15 Hz > 2 Hz. The results suggest that an increased release of CCK-8 following EA may limit the effect of opioid peptides, and that the CCK-B receptor mediates the anti-opioid effect of CCK-8 in rat spinal cord.

Acupuncture Analgesia↗
PubMed1993

[Potentiation of morphine- and ohmefentanyl-induced analgesia by cholecystokinin receptor antagonists in rat].

It has been reported that intrathecal (i.t.) injection of CCK-8 showed a marked antagonism to analgesic effects mediated by mu-opioid receptors in rat. The present study was performed to ascertain whether the blockade of endogenously released CCK-8 by potent and selective CCK-A antagonist devazepide and CCK-B antagonist L-365260 would affect opioid analgesia at the spinal cord level. A marked potentiation of the analgesic effect induced by morphine (4 mg/kg, sc) was produced by i.t. injection of 100 ng devazepide or 2.5 ng L-365260. Dose-response curves for the enhancement of the two drugs on morphine analgesia were bell-shaped. Intrathecal injection of 66 ng devazepide or 1.25 ng L-365260 was also shown to potentiate the analgesic effect induced by the selective mu-opioid agonist ohmefentanyl (OMF) (32 ng, i.t.). The dose-response curves were also bell-shaped. Devazepide or L-365260 per se produced no significant changes in rat tail flick latency (TFL). The above results are interpreted to mean that endogenously released CCK-8 in the spinal cord plays an antagonistic role to opioid analgesia, and it is the CCK-B receptors that mediate the anti-opioid effect since the dose of devazepide is 40-50 times higher than that of L-365260.

Analgesics↗
PubMed1992

A maize cryptic Ac-homologous sequence derived from an Activator transposable element does not transpose.

Sequences sharing homology to the transposable element Activator (Ac) are prevalent in the maize genome. A cryptic Ac-like DNA, cAc-11, was isolated from the maize inbred line 4Co63 and sequenced. Cryptic Ac-11 has over 90% homology to known Ac sequences and contains an 11 bp inverted terminal repeat flanked by an 8 bp target site duplication, which are characteristics of Ac and Dissociation (Ds) transposable elements. Unlike the active Ac element, which encodes a transposase, the corresponding sequence in cAc-11 has no significant open reading frame. A 44 bp tandem repeat was found at one end of cAc-11, which might be a result of aberrant transposition. The sequence data suggest that cAc-11 may represent a remnant of an Ac or a Ds element. Sequences homologous to cAc-11 can be detected in many maize inbred lines. In contrast to canonical Ac elements, cAc-11 DNA in the maize genome is hypermethylated and does not transpose even in the presence of an active Ac element.

Base Sequence↗
PubMed1992

Accelerated expression of cholecystokinin gene in the brain of rats rendered tolerant to morphine.

Results from behavioural studies have shown that central cholecystokinin octapeptide (CCK-8) is a powerful antagonist against opioid effects and that an increased release of central CCK-8 plays an important role in the mechanisms of tolerance to morphine analgesia. No information is available concerning the rate of biosynthesis of CCK-8 in response to chronic morphine administration. Blot hybridization experiments made in the present study revealed a marked increase in preproCCK mRNA in the brain of rats receiving chronic morphine treatment for 1, 3 and 6 days, showing an increment of 52% (p < 0.05), 62% (p < 0.05) and 97% (p < 0.01) respectively. The results suggest that an acceleration of the expression of the CCK gene during long-term morphine treatment might constitute one of the mechanisms for morphine tolerance.

Animals↗
PubMed1992

[Gastrointestinal dysfunction and peroral nutrition after severe burns].

The patient with severe burns is characterized by a hypermetabolic response, and degree of which is proportional to the magnitude of burns. Major thermal injury is often associated with gastrointestinal dysfunction. Failure to provide adequate caloric intake by both enteral and parenteral routes will results in pronounced weight loss, delayed wound healing, depression of host resistance and cellular dysfunction. We analysed 676 burn patients with TBSA over 50%, and found regular changes in gastrointestinal function with endoscopy and also at autopsy. A new dietary programme is described in the article.

Burns↗
PubMed1992

[Observation of prosthesis movement after implantation of the bipolar artificial femoral head].

The follow-up results of the movement of two components of hip prosthesis in 30 cases at different times after implantation of bipolar artificial femoral head were reported in this paper. It was demonstrated that the motion at both bearing surfaces in all cases was present 3 months-3 years after operation, and the motion range was not reduced with time. Therefore, the movement of bipolar artificial femoral head could be maintained within at least 3 years after implantation.

Aged↗
PubMed1991

[Blood circulation of the "super-thin" skin flap with preserved subdermal vascular network and its clinical application].

For the study of the blood circulation of the superthin skin flap, arterial perfusion of Chinese black ink was performed in 24 cadavers. From 1984 to 1990, "super-thin" skin flap transplantations have been done in 18 patients with deep injuries as a result of electric contact burn, wringer injuries, or chemical burns. The flap taken from thoracic, abdominal, or upper arm regions was trimmed before transfer, and 2 mm thickness of fat was left attached to the subdermal vascular network. The largest super-thin skin flap of the inguinal region was 7 cm in breadth at the pedicle, 15 cm in length and 20 cm in width at the distal part. All of these flaps survived after transfer. Division of the pedicles was performed 3-5 days postoperatively. The cosmetic and functional results were all satisfactory.

Adolescent↗
PubMed1989

Comparison of exon 5 sequences from 35 class I genes of the BALB/c mouse.

DNA sequences of the fifth exon, which encodes the transmembrane domain, were determined for the BALB/c mouse class I MHC genes and used to study the relationships between them. Based on nucleotide sequence similarity, the exon 5 sequences can be divided into seven groups. Although most members within each group are at least 80% similar to each other, comparison between groups reveals that the groups share little similarity. However, in spite of the extensive variation of the fifth exon sequences, analysis of their predicted amino acid translations reveals that only four class I gene fifth exons have frameshifts or stop codons that terminate their translation and prevent them from encoding a domain that is both hydrophobic and long enough to span a lipid bilayer. Exactly 27 of the remaining fifth exons could encode a domain that is similar to those of the transplantation antigens in that it consists of a proline-rich connecting peptide, a transmembrane segment, and a cytoplasmic portion with membrane-anchoring basic residues. The conservation of this motif in the majority of the fifth exon translations in spite of extensive variation suggests that selective pressure exists for these exons to maintain their ability to encode a functional transmembrane domain, raising the possibility that many of the nonclassical class I genes encode functionally important products.

Amino Acid Sequence↗
PubMed1988

Molecular linkage of the Ly-3 and Ly-2 genes. Requirement of Ly-2 for Ly-3 surface expression.

We have isolated the Ly-3 gene by chromosomal walking from the previously cloned Ly-2 gene. These genes are shown to be 36 kb apart and in the same transcriptional orientation. Transfection of the Ly-3 gene into mouse L cells results in cell surface expression of Ly-3 protein only in the presence of Ly-2 (or its human homolog, CD8), although Ly-2 surface expression is not similarly dependent on Ly-3. cDNA clones encoding Ly-3 have been isolated and sequenced and show little sequence similarity to Ly-2, whereas both Ly-2 and Ly-3 are homologous to Ig variable regions. One cDNA clone encodes a form of Ly-3 lacking a transmembrane region. Although two alleles of Ly-3 have been previously defined serologically, Northern blot analyses of Ly-3 mRNA from a series of inbred mouse strains show unusual polymorphisms in the lengths of Ly-3 mRNA species defining at least three allelic variants of this gene.

Alleles↗
PubMed1988

The use of free flaps in burn patients: experiences with 70 flaps in 65 patients.

A series of 70 microvascular free flaps employed in 65 burn patients is presented. The total survival incidence of the flaps was 87 percent. Satisfactory wound healing was achieved in 80 percent of a total of 54 flaps in fresh burn patients. In the 16 patients with healed burns, flap survival was 100 percent with satisfactory functional and cosmetic results. The cruxes of dealing with difficult fourth-degree burns by using microvascular free flaps and our special considerations about the indications and overall morbidities of the donor site are discussed. This large-series report confirms other occasional reports on the use of free flaps in burn patients. It is our belief that the microvascular free flap is the most expeditious means of dealing with refractory burn wounds, even when more conventional techniques are available. In certain cases, the microvascular procedure is the only method that can salvage an extremity.

Accidents, Occupational↗
PubMed1988

Differential expression of the ASGM1 antigen on anti-reovirus and alloreactive cytotoxic T lymphocytes (CTL).

Anti-reovirus cytotoxic effectors were found to be: (i) H-2 restricted; (ii) virus specific; (iii) non-lytic (in 4 h) for natural killer (NK)-sensitive YAC-1 cells; and (iv) positive for the Thy-1 and Lyt-2 lymphocyte markers. Thus, anti-reovirus cytotoxic effectors have the functional and phenotype characteristics of cytotoxic T lymphocyte (CTL). A significant fraction of anti-viral CTL, as well as alloreactive CTL, were also found to be positive for the asialo GM1 (ASGM1) cell surface antigen, generally considered to be a NK cell marker. ASGM1 expression on these CTL, as determined by sensitivity to antibody plus complement (C), appeared to be highly variable and dependent on two factors-the nature of the antigenic stimulus (viral vs. alloantigen), and the mouse strain from which the CTL originated. Thus, ASGM1 antigen expression on CTL appears to be regulated and may be under the control of lymphokines, development differentiation signals and/or other strain-dependent genetic factors.

Animals↗
PubMed1986

Amino acid sequence of the testosterone-regulated mouse kidney RP2 protein deduced from its complementary DNA sequence.

The major forms of testosterone-regulated RP2 messenger RNA (also known as MAK mRNA and pMK908) in the mouse kidney were characterized by examining cDNA and genomic clones. Three sizes of RP2 mRNA are detected by Northern blot analysis and these were shown to result from polyadenylation at three distinct sites within the primary transcript of this single-copy gene. The complete RP2 mRNA sequence was obtained from overlapping cDNA clones, revealing an open reading frame of 357 amino acids that corresponds to a protein of 40,365 daltons. The detection of RP2 mRNA in all tissues examined to date suggests that the RP2 protein may function in a housekeeping role in all cells. This is supported by the finding of a high percentage of G + C residues at the 5' end of the gene, including a sequence homologous to the binding site of the transcription factor Sp1, which has been suggested to affect the regulation of other housekeeping genes that have been characterized. An examination of the amino acid sequence indicates that the RP2 protein is proline-rich and is composed of alternating alpha-helix and beta-sheet regions. RP2 is probably not integrated into a membrane structure in the cell as it does not appear to contain hydrophobic regions capable of spanning a membrane.

Amino Acid Sequence↗
PubMed1985

Molecular basis of the dm1 mutation in the major histocompatibility complex of the mouse: a D/L hybrid gene.

The H-2dm1 mutation is unique among all described H-2 mutations in that two transplantation antigens, the H-2Dd and the H-2Ld, are affected. Here, we show that the mutant gene, Ddm1, is formed by fusion of the 5' part of the Dd gene and the 3' part of the Ld gene, with the region in between deleted. The recombination junction is located in the third exon, which encodes the alpha 2 region of the protein. When the hybrid gene is transfected into mouse L cells, serological and biochemical analyses indicate the Ddm1 antigen expressed in the transformant line is identical to the mutant molecule in dm1 spleen cells. These results demonstrate that the D/L hybrid gene is most likely responsible for the dm1 mutant phenotype.

Amino Acid Sequence↗
PubMed1985

Candida infection in severe burns.

Candida infection has become an important cause of morbidity and death in burned or immunosuppressed patients. Two patients with extensive burn complicated with Candida infection are presented, along with the risk factors, diagnostic procedures, and current methods of treatment.

Adult↗