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Biomedical subjects

Y Gu

Publications and source records attributed to Y Gu.

At least 217 records · Page 12Linked to original sources
PubMed1998

[Clinical application of the reversed digital artery island flap containing palmar digital vein].

In order to introduce a novel reversed digital artery island flap, it was used in 13 cases involving 17 digital skin defects since 1993, in which digital skin defects were covered by a reversed digital artery island flap, a comparative study was made between the flaps with or without a palmar digital vein. The results showed that the 17 island flaps were all survived, and during the early stage after operation, the incidence of venous crisis in the flaps without palmar digital vein was 87.5% (7/8) while that in the flaps with the vein was only 11.1% (1/9), so, it was concluded that the reversed digital artery island flap containing a palmar digital vein could obviously reduce the incidence of venous crisis and improve the survival of the flap.

Adolescent↗
PubMed1998

[The hemodynamic changes after end-to-end anastomosis of the small arteries in rats].

The hemodynamics changes of the common carotid arteries in 10 SD rats were measured with a color doppler flowmetry in an attempt to define the changes resulting from end-to-end anastomosis. The left common carotid arteries were divided and followed by end-to-end anastomosis. The systolic mean peak velocities in the left arteries were measured at the proximal, distal and anastomotic sites and in the right intact arteries as well at 6, 12, 24, 48, 72 and 120 hours after repair. The percentage of area reduction at anastomosis was calculated from these data. The results indicated that the systolic mean peak velocity at the anastomotic sites was significantly increased as compared to the velocity at the proximal, distal and contralateral sites (P < 0.05). The velocity at the distal sites was significantly lower than that from the proximal and contralateral sites (P < 0.05), the mean percentage of the reduction was 33.18% and 33.33%, respectively. From 6 hours to 120 hours after anastomosis of arteries there was various degree of narrowing at the site of anastomosis. The mean per cent of stenosis was 42.48%. It was concluded that from 6 to 120 hours after end-to-end anastomosis of the small arteries, the velocity at the anastomotic site was increased as compared to the velocities at pre- and post-anastomotic sites. The increase of velocity at the site of anatomosis was caused by stenosis at the anastomosis.

Anastomosis, Surgical↗
PubMed1998

[Embryonic motoneurons transplanted into denervated skeletal muscles].

OBJECTIVE: To observe the living situation of homografting embryonic motoneurons in denervated skeletal muscles. METHODS: We transplanted dissociated ventral spinal cord cells from 12 embryonic days rats prelabeled with 5-bromo-2-deoxyuridine(Brdur) into denervated skeletal muscles of adult rats. The denervated skeletal muscles were collected at 9 and 22 weeks respectively, and Nissl, acetylcholinesterases immunocytochemistry and ATPase staining were used to show the transplanted embryonic motoneurons and the morphography of muscle fibers. RESULTS: Transplanted embryonic motoneurons could survive, extend out long axons, and form neuromuscular junctions with muscle fibers. Type grouping fibers with bigger transverse area were also observed in the experimental group. Muscle fibers were much smaller and did not form fiber type grouping in the control group. CONCLUSION: Homografting embryonic motoneurons could survive well and reinnervate the denervated skeletal muscles.

Animals↗
PubMed1998

Division of C8 nerve root for treatment of spastic cerebral palsy in the upper limbs: a preliminary report.

OBJECTIVE: To investigate the effect of C8 nerve root division on the treatment of spastic cerebral palsy in the upper limbs. METHODS: Two patients were treated with division of the C8 never root. Supraclavicular incision was made to expose the C5-T1 nerve roots. The intraoperative electromyographic recording technique was used to monitor the responses from the flexor digitorum and flexor carpi ulnaris muscle groups simultaneously. The C5-T1 nerve roots were stimulated and the evoked muscle amplitude potentials (EMAP) were recorded from the muscle groups. The EMAP of the muscle groups obtained during electrical stimulation of the C8 nerve root was the largest, which was used as the basis for C8 nerve root division. RESULTS: Division of the C8 nerve root slightly affected the function of the upper limb, and reduced the muscle tone of the flexor wrist and digitorum. CONCLUSION: Division of the C8 nerve root can reduce the muscle tone of the flexor wrist and digitorum in a short time. The long-term effects need to be followed up further.

Adolescent↗
PubMed1998

The protective effect of procaine blocking on nerve-electrophysiological study during operation.

OBJECTIVE: To clinically evaluate the protective effect of procaine blocking on nerves. METHODS: Electrophysiological examination before and after procaine blocking was conducted on 32 nerves during operation, 18 of which were donor nerves and 14 were injured ones. RESULTS: The latency of somatosensory evoked potentials (SEPs) was lengthened (15.30%) and the amplitude was lowered (18.47) after procaine blocking. Compared with the values before procaine blocking, the differences were significant (P < 0.01 and P < 0.05, respectively). SEP waves disappeared after procaine blocking in some cases (28.13%). CONCLUSION: Latency of SEP is lengthened and amplitude is lowered after procaine blocking. In some cases, SEPs even disappear.

Accessory Nerve↗
PubMed1998

[Observation of electronystagmogram in pilots under vestibular stimulation].

The relationship between electronystagmogram(ENG) and intensity of vestibular stimulation was observed in 62 pilots. 31 pilots received low intensity vestibular stimulation and the other 31 pilots received higher intensity vestibular stimulation. Electronystagmogram were recorded and analysed. The results showed that there was no relationship between the ENG parameters and stimulation intensity, but both slow phase and fast phase velocities and amplitudes were lower under Coriolis acceleration stimulus, while all of them were higher under angular acceleration and angular stimulations. It was also found that the fast phase amplitude of ENG was related to motion sickness symptoms of the subjects.

Acceleration↗
PubMed1998

[Effects of vestibular stimulus on heart rate variability].

Possible effects of vestibular stimulation autonomic nerve function in pilots were studied by observing changes of Heart Rate Variability (HRV). Time domain and frequency domain analyses demonstrated that the primarily averages, standard deviation of the HRV averages(SD), least or greatest value, deviation of greatest minus least value, interrelated averages, square root of the mean of the sum of squares of differences between adjacent R-R intervals (RMSSD), total power(TP), low frequency(LF), high frequency(HF), LF/TP, HF/TP, and LF/HF all had significant increase or decrease (P <0.05 - <0.01) and the degrees of changes were related to the intensity of the stimulations.

Adult↗
PubMed1998

[Surgical injuries influence on release of endothelin-1 and local blood perfusion of amputated extremities].

OBJECTIVE: To observe influence of amputations and surgical injuries on synthesis and release of endothelium-derived endothelin-1, and local blood perfusion of amputated extremities. METHOD: The plasma endothelin-1 concentrations of 18 patients preoperatively and postoperatively and the endothelin-1 concentrations of femoral artery wall in 80 SD rats were determined using radioimmunoassay technique before and after amputation. Local blood perfusion of amputated extremities in rats were determined using laser Doppler flowmetry. RESULT: The plasma endothelin-1 concentrations in the patients with surgical injuries increased obviously, reached peak value at fourth hour postoperatively, being approximately 3 times of that of the control group. The endothelin-1 concentrations of femoral artery wall in amputated rats also increased, reached peak value at second hour after amputation, being approximately 2 times of that of the control group, and then decreased gradually, at the same time the local blood perfusion decreased, reached its lowest value at second hour after amputation, being only 25 percent of the control value. The endothelin-1 concentration of rat femoral artery wall was negatively relative to local blood perfusion (r = -0.83). CONCLUSION: Injuries enhance synthesis and release of endothelin-1. It is probably one of the main causes of vasospasm after injuries.

Adolescent↗
PubMed1998

[Anatomical study and clinical observation of thoracic outlet syndrome].

OBJECTIVE: To investigate the etiology of thoracic outlet syndrome (TOS) from the point of anatomical and clinical view. METHOD: Anatomical study was made on both sides of 30 cadavers. The minimus scalene muscle and the insertions of anterior and middle scalene muscle were dissected and observed. Clinically, 45 cases of thoracic outlet syndrome (TOS) were treated and followed up. RESULT: The minimus scalene muscle was found in 88.3% of the cadavers. T(1) nerve root or the lower trunk of brachial plexus crossed the first rib just over the proximal tendinous part of minimus scalene muscle. Of 45 cases of TOS 34 presented neck-shoulder-pain 17 had. Unchanged symptoms postoperatively, and 7 had aggravated symptoms. Of the recent 8 cases of TOS, 7 presented neck-shoulder-pain. However, the symptom remained in only case after the resection of the tendinous tissue around 5, 6 nerve root from anterior and middle scalene muscle. CONCLUSION: The tendinous tissue of minimus muscle is the cause of the compression of T(1) nerve root or the lower trunk of the brachial plexus. The crossed tendinous origins from the anterior and posterior tubercle of C(4,5) transverse process is the cause of the compression of C(5,6) nerve root or the upper trunk of brachial plexus.

Adolescent↗
PubMed1998

[Application of computer simulation in the study of vibrational distributions for the products from energy transfer reaction].

The method of computer simulation in the study of vibrational distributions for the products from the energy transfer reaction is discussed. Taking the Ar (3P(0.2)) + PCl --> PCl (A3II) reaction as an example, we analysed the process of the simulation and the problems that should be paid attention to. The Franck-Condon factors of PCl (A3II --> X3sigma(-1)) are reported for the first time.

English Abstract↗
PubMed1997

Mercury-sensitive residues and pore site in AQP3 water channel.

Water channel function of all aquaporins (AQPs) but AQP4 can be inhibited by mercurial reagents. Mercurial reagents are believed to bind specifically to cysteine residues and block the aqueous pore of AQPs. Because of the low homology of AQP3 to other AQPs, it is not certain whether the pore structure of AQP3 is similar to that of the others. Determination of mercury-sensitive cysteine residues in AQP3 and comparison with those in other AQPs will help to resolve this question. When AQP3 was expressed in Xenopus oocytes, incubation with 0.3 mM HgCl2 decreased its osmotic water permability (Pf) by approximately 30%. To identify the mercury-sensitive site, six individual cysteine residues in human AQP3 (at positions 11, 29, 40, 91, 174, and 267) were altered by site-directed mutagenesis. Mutants of C11S and C11A had a similar basal Pf to wild-type but acquired mercury resistance. Replacement of Cys-11 with Trp, which possesses a large side chain, did not change Pf. Mercurial inhibition of Pf was still observed in five other Cys-to-Ser mutants. These results suggest that Cys-11 is the mercury-sensitive residue in AQP3 and that this residue might be independent of water channel function. Mutation of Tyr-212, a position corresponding to the mercury-sensitive residues in AQP1 and AQP2, to cysteine enhanced the mercurial inhibition of Pf. Y212W had no water channel activity. Expression of AQP3 increased glycerol permeability (Pgly) 3.1-fold, whereas Pgly of Y212W-expressing oocytes was similar to Pgly of control oocytes. Cysteine mutation at Tyr-212 increased the inhibitory effect of mercury on Pgly. These results suggest that the structure of the aqueous pore of AQP3 resembles those of AQP1 and AQP2 and support the hypothesis that water and small molecules share a common pore in AQP3.

Animals↗
PubMed1997

An Electrical Suspension Method for Measuring the Electric Charge on Small Silicone Oil Droplets Dispersed in Aqueous Solutions

The electric charge on small liquid droplets dispersed in another immiscible liquid is of fundamental interest in various colloidal and interfacial phenomena and industrial processes. In this paper, the authors present a new experimental method to measure the charge on small silicone oil droplets in aqueous solutions. Basically, an oil droplet was kept stationary inside a test cell between two electrode plates by application of an electric field of an appropriate polarity and strength. Thus, the electric charge on the oil droplet was determined from the force balance among the electrical force, the gravitational force, and the buoyancy force exerted on it. By using the electrical suspension method, the effects of two different silicone oils, pH values, valences, and concentrations of three different electrolytes on the measured electric charge were investigated. One of the two silicone oils is heavier (rho1 = 1050 kg m-3) and the other is lighter (rho2 = 963 kg m-3) than the aqueous solutions. There was an appreciable difference between the measured electric charges for the two silicone oils. The point of zero charge (pzc) for the heavier oil droplets was found to be pH approximately 5.0, which is essentially the same as the value for the mineral oil droplets in the oil-in-water (O/W) emulsions reported by other researchers. It was also observed that the electric charge depends strongly on not only the concentrations but also the ionic valences of electrolytes added to the solutions. More specifically, divalent and trivalent cations, such as Ca2+ and Al3+, were more readily adsorbed on the oil-water interface. Therefore, their effects were more pronounced than that of monovalent cations, Na+, on reducing the negative charge or even reversing the charge polarity as their ionic concentrations increase, in accordance with the valence difference. Copyright 1997 Academic Press. Copyright 1997Academic Press

Journal Article↗
PubMed1997

A new iterative procedure for combining direct methods with solvent flattening - dealing with the phase ambiguity in protein crystallography.

A new procedure for combining direct methods with the solvent-flattening technique is proposed for phasing single isomorphous replacement (SIR) or one-wavelength anomalous scattering (OAS) data of proteins. The new procedure differs from the previous one [Zheng, Zheng, Gu, Mo, Fan & Hao (1997). Acta Cryst. D53, 49-55] in that the direct method not only provides input phases to but also accepts feedback phases from solvent flattening, thus forming an iterative process for breaking the ambiguities and refining the values of phases. The new procedure was tested with the experimental SIR data of the known structure ribonuclease Sa. For the strongest 1000 of the total 7264 reflections, the mean F(obs)-weighted phase error is 7.5 and 9.4 degrees lower than that of the previous procedure and that of solvent flattening alone, respectively.

Journal Article↗
PubMed1997

Involvement of caspase-1 and caspase-3 in the production and processing of mature human interleukin 18 in monocytic THP.1 cells.

Recently, human interleukin 18 (hIL-18) cDNA was cloned, and the recombinant protein with a tentatively assigned NH2-terminal amino acid sequence was generated. However, natural hIL-18 has not yet been isolated, and its cellular processing is therefore still unclear. To clarify this, we purified natural hIL-18 from the cytosolic extract of monocytic THP.1 cells. Natural hIL-18 exhibited a molecular mass of 18.2 kDa, and the NH2-terminal amino acid was Tyr37. Biological activities of the purified protein were identical to those of recombinant hIL-18 with respect to the enhancement of natural killer cell cytotoxicity and interferon-gamma production by human peripheral blood mononuclear cells. We also found two precursor hIL-18 (prohIL-18)-processing activities in the cytosol of THP.1 cells. These activities were blocked separately by the caspase inhibitors Ac-YVAD-CHO and Ac-DEVD-CHO. Further analyses of the partially purified enzymes revealed that one is caspase-1, which cleaves prohIL-18 at the Asp36-Tyr37 site to generate the mature hIL-18, and the other is caspase-3, which cleaves both precursor and mature hIL-18 at Asp71-Ser72 and Asp76-Asn77 to generate biologically inactive products. These results suggest that the production and processing of natural hIL-18 are regulated by two processing enzymes, caspase-1 and caspase-3, in THP.1 cells.

Amino Acid Sequence↗
PubMed1997

Cloning and functional expression of a new water channel abundantly expressed in the testis permeable to water, glycerol, and urea.

A new member of the aquaporin (AQP) family has been identified from rat testis. This gene, referred as aquaporin 7 (AQP7), encodes a 269-amino acid protein that contained the conserved NPA motifs of MIP family proteins. AQP7 has the amino acid sequence homology with other aquaporins ( approximately 30%), and it is highest with AQP3 (48%), suggesting that both AQP3 and AQP7 belong to a subfamily in the MIP family. Injection of AQP7-cRNA into Xenopus oocytes expressed a 26-kDa protein detected by immunoblotting. The expression of AQP7 in oocytes stimulated the osmotic water permeability by 10-fold which was not inhibited by 0.3 mM mercury chloride. The Arrhenius activation energy for the stimulated water permeability was low (2.1 kcal/mol). AQP7 also facilitated glycerol and urea transport by 5- and 9-fold, respectively. The activation energy for glycerol was also low (5.3 kcal/mol after the correction of the endogenous glycerol permeability of oocytes). Northern blot analysis revealed a 1.5-kilobase pair transcript expressed abundantly in testis. In situ hybridization of testis revealed the expression of AQP7 at late spermatids in seminiferous tubules. The immunohistochemistry of testis localized the AQP7 expression at late spermatids and at maturing sperms. AQP7 may play an important role in sperm function.

Amino Acid Sequence↗
PubMed1997

Ku70-deficient embryonic stem cells have increased ionizing radiosensitivity, defective DNA end-binding activity, and inability to support V(D)J recombination.

V(D)J recombination requires both lymphoid-specific and generally expressed enzymatic activities. All three known generally expressed activities involved in V(D)J recombination are also involved in DNA double-strand break repair (DSBR). Two of these are components of the DNA-dependent protein kinase (DNA-PK) and include Ku80 and DNA-PK catalytic subunit (DNA-PKcs); the third, XRCC4, is a protein of unknown function. The Ku70 protein is an additional component of DNA-PK; Ku70 forms a heterodimer with Ku80 to generate the DNA end-binding component of the enzyme. To test putative functions for Ku70, we have used gene-targeted mutation to generate a murine embryonic stem cell line which lacks Ku70 expression. We find that the Ku70(-/-) cells produce no detectable Ku70 and very little Ku80, suggesting a direct interrelationship between their levels. Correspondingly, these cells lack the nonspecific DNA end-binding activity associated with Ku. Significantly, the Ku70(-/-) embryonic stem cells have markedly increased sensitivity to gamma-irradiation relative to Ku70(+/-) or wild-type embryonic stem cells. Furthermore, the Ku70(-/-) cells lack the ability to effectively rejoin signal and coding ends liberated in transiently introduced V(D)J recombination substrates by enforced RAG-1 and RAG-2 expression. We conclude that the Ku70 gene product is involved in DSBR and V(D)J recombination and confirm that the Ku70 gene can be classified as a member of the x-ray cross-complementation group 6 (XRCC6). Potential differences between the Ku70(-/-) and Ku80(-/-) V(D)J recombination defects are discussed.

Animals↗
PubMed1997

Substrate and inhibitor specificity of interleukin-1 beta-converting enzyme and related caspases.

Interleukin-1beta-converting enzyme (ICE) is a novel cysteine protease responsible for the cleavage of pre-interleukin-1beta (pre-IL-1beta) to the mature cytokine and a member of a family of related proteases (the caspases) that includes the Caenorhabditis elegans cell death gene product, CED-3. In addition to their sequence homology, these cysteine proteases display an unusual substrate specificity for peptidyl sequences with a P1 aspartate residue. We have examined the kinetics of processing pre-IL-1beta to the mature form by ICE and three of its homologs, TX, CPP-32, and CMH-1. Of the ICE homologs, only TX processes pre-IL-1beta, albeit with a catalytic efficiency 250-fold less than ICE itself. We also investigated the ability of these four proteases to process poly(ADP-ribose) polymerase, a DNA repair enzyme that is cleaved within minutes of the onset of apoptosis. Every caspase examined cleaves PARP, with catalytic efficiencies ranging from 2.3 x 10(6) M-1 s-1 for CPP32 to 1.0 x 10(3) M-1 s-1 for TX. In addition, we report kinetic constants for several reversible inhibitors and irreversible inactivators, which have been used to implicate one or more caspases in the apoptotic proteolysis cascade. Ac-Asp-Glu-Val-Asp aldehyde (DEVD-CHO) is a potent inhibitor of CPP-32 with a Ki value of 0.5 nM, but is also potent as inhibitor of CMH-1 (Ki = 35 nM) and ICE (Ki = 15 nM). The x-ray crystal structure of DEVD-CHO complexed to ICE presented here reveals electrostatic interactions not present in the Ac-YVAD-CHO co-complex structure (Wilson, K. P., Black, J.-A. F., Thomson, J. A., Kim, E. E., Griffith, J. P., Navia, M. A., Murcko, M. A., Chambers, S. P., Aldape, R. A., Raybuck, S. A., and Livingston, D. J. (1994) Nature 370, 270-275), accounting for the surprising potency of this inhibitor against ICE.

Animals↗