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Biomedical subjects

Y Ai

Publications and source records attributed to Y Ai.

At least 37 records · Page 2Linked to original sources
PubMed1997

High expression and activation of MAP kinase-activated protein kinase 2 in cardiac muscle cells.

Recently, three mammalian mitogen-activated protein (MAP) kinases, ERK, SAPK/JNK, and p38/HOG-1 have been identified, each with apparently unique signal transduction pathways. The p38 MAP kinase mediates an intracellular stress-activated signaling pathway by regulating down-stream molecules, such as MAP kinase-activated protein (MAPKAP) kinase 2. To study the tissue specificity of MAPKAP kinase 2, mRNA blots containing multiple human tissues were hybridized with a specific oligonucleotide probe corresponding to human MAPKAP kinase 2. The Northern blot analysis revealed that two mRNA species of MAPKAP kinase 2, with sizes of 4.8 and 3.3 kb, were expressed in high levels in both human heart and skeletal muscle tissues. To better understand how MAPKAP kinase 2 is regulated in myocardium, cultured rat cardiac myoblast (H9c2) cells were stimulated with heat shock, H2O2-induced oxidative stress, or phorbol ester (PMA). Enzymatic activity of cellular MAPKAP kinase 2 in the cell lysates was evaluated using an in vitro kinase assay. Exposure of H9c2 cells to heat shock or oxidative stress induced a transient increase of cellular MAPKAP kinase 2 activity, which reached its peak level within 5 min. In contrast, stimulation of H9c2 cells with PMA, a potential myocardial hypertrophic factor, induced a sustained increase of cellular MAPKAP kinase 2 activity that was detectable for over 1 h. In addition, in vitro protein phosphorylation analysis with recombinant MAPKAP kinase 2 showed that small heat shock protein (hsp25) served as a major substrate molecule for the kinase in H9c2 cells and the protein phosphorylation of cellular hsp25 was stimulated by H2O2-induced oxidative stress or PMA treatment in intact H9c2 cells. Moreover, exposure of H9c2 cells to H2O2-induced oxidative stress or PMA rapidly activated cellular p38 MAP kinase as detected by the induced protein phosphorylation of the kinase. Taken together, these results strongly suggest that MAPKAP kinase 2 may be involved in stress-activated signal transduction in myocardium.

Animals↗
PubMed1997

[Scalp expansion in treatment of scalp defect with skull exposure].

We repaired the scalp defect and skull exposure with scalp expansion. The technique consisted of two stages. First, expander was implaned an then N. S injected to its enough volume. The size of the expander was estimated by the formula that 1 cm2 needs 4 ml expansive volume. The incision was made at normal skin. Second flap was transferred. The expander was removed and the external skull which was necrotic severed. There were five patient with eight flaps at all, followed up for 6 months to 1 year. The hair grew. The results were satisfactory. This method not only treated the disease, but also avoided alopecia.

Adolescent↗
PubMed1997

Hybridization dominance of kinetics in recombinant ATH-1376 obtained via protoplast fusion between Aspergillus niger and Trichoderma reesei.

Comparisons of the kinetics of mycelium growth, cellulase biosynthesis, and the degradation of filter paper to accumulate reducing-sugar by the filtrates of cultures were carried out among the recombinant strain ATH-1376 and its two parents, Aspergillus niger AMS11 and Trichoderma reesei QM9414. The results showed that both the specific mycelium growth rate and the cellulase biosynthesis rate of the recombinant were dramatically dominant over those of the two parents. In addition, the negative correlation between the specific mycelium growth rate and the cellulase biosynthesis rate of the recombinant ATH-1376 was much lower than those of its parents. In terms of the amount of reducing-sugar accumulated from the hydrolysis of filter paper by culture filtrates, there were great differences among the three different treatments, i.e., fermentation filtrate of single parental strain, mixture of the fermentation filtrates from two parental strains with different ratios (v:v), and filtrate from the mixed culture of the two parental strains. Out of these, the second approach, particularly with the ratio of 1:1, was best for the accumulation of reducing sugar. Within various tested periods of enzymic hydrolysis, the amounts of reducing-sugar produced by the recombinant were 1.19 to 2.26 times as much as the maximum amounts produced in parallel by the mixture of filtrates (1:1) from separate fermentations of the two parental strains. These results suggested that constructing the engineered strains with hybridization dominance of these two typical genera of far-heredity could be effective to overcome the great deficiencies of routine mixculture, single-strain fermentation, or double fed-batch fermentations.

Aspergillus niger↗
PubMed1996

Activation of MAP kinase-activated protein kinase 2 in human neutrophils after phorbol ester or fMLP peptide stimulation.

In response to extracellular stimulation, one of the earliest events in human neutrophils is protein phosphorylation, which mediates signal transduction and leads to the regulation of cellular functions. Mitogen-activated protein (MAP) kinases are rapidly activated by a variety of mitogens, cytokines, and stresses. The activated MAP kinases in turn regulate their substrate molecules by phosphorylation. MAP kinase-activated protein (MAPKAP) kinase 2, a Ser/Thr kinase, has been shown to be phosphorylated by p38 MAP kinase both in vivo and in vitro. Phosphorylation of the Thr-334 site of MAPKAP kinase 2 results in a conformational change with subsequent activation of the enzyme. To better define the role of MAPKAP kinase 2 in the activation of human neutrophils, its enzymatic activity was measured after stimulation by either a phorbol ester (phorbol myristate acetate [PMA]), a potent protein kinase C activator, or the tripeptide fMLP, which is a chemotactic factor. The in vitro kinase assays indicate that both PMA and fMLP stimulated a transient increase in the enzymatic activity of cellular MAPKAP kinase 2. The induced kinase activation was concentration-dependent and reached a maximum at 5 minutes for PMA and 1 minute for fMLP. To identify potential substrate molecules for MAPKAP kinase 2, a highly active kinase mutant was generated by mutating the MAP kinase phosphorylation site in the C-terminal region. The replacement of threonine 334 with alanine resulted in a marked augmentation of catalytic activity. Analysis of in vitro protein phosphorylation in the presence of the active kinase indicates that a 60-kD cytosolic protein (p60) was markedly phosphorylated and served as the major substrate for MAPKAP kinase 2 in human neutrophils. Based on the MAPKAP kinase 2 phosphorylation site of Hsp27, a competitive inhibitory peptide was synthesized. This competitive inhibitory peptide specifically inhibited MAPKAP kinase 2 enzymatic activity, as well as the in vitro and in vivo kinase-induced p60 phosphorylation. To assess the contribution of MAPKAP kinase 2 in neutrophil function, the oxidative burst response after manipulation of endogenous kinase activity was measured. Intracellular delivery of the competitive inhibitory peptide into human neutrophils reduced both PMA- and fMLP-stimulated superoxide anion production. Thus, the results strongly suggest that MAPKAP kinase 2 is involved in the activation of human neutrophils.

Amino Acid Sequence↗
PubMed1996

Research on soft-tissue expander permeability to metronidazole and procaine.

This in vitro study was designed to determine if in fact silicone expanders are readily permeable to metronidazole and procaine. The expanders were filled with 0.2% metronidazole or 2% procaine through the filler valves and then immersed wholly in normal saline. At several intervals over 120 hours, a certain amount of the surrounding saline was sampled and the drug levels subsequently determined. In this study, the silicone expanders were indeed readily permeable to the drugs, as measured with an ultraviolet spectrophotometer. A consistent diffusion curve was demonstrated. The rate of diffusion of a drug is inversely proportional to its molecular weight; i.e., the smaller the given drug's molecular weight, the greater is its ability to permeate an expander. In view of this, in the course of expansion, 0.2% metronidazole could be used in clinical expansion instead of normal saline, and a certain amount of antibiotic would diffuse out of the expander to prevent and control the infection.

Humans↗
PubMed1996

Fine structure of the human galactokinase GALK1 gene.

Defects in the human GALK1 gene result in galactokinase deficiency and cataract formation. We have isolated this gene and established its structural organization. The gene contains 8 exons and spans approximately 7.3 kb of genomic DNA. The GALK1 promoter was localized and found to have many features in common with other housekeeping genes, including high GC content, several copies of the binding site for the Sp1 transcription factor, and the absence of TATA-box and CCAAT-box motifs typically present in eukaryotic Pol II promoters. Analysis by 5'-RACE PCR indicates that the GALK1 mRNA is heterogeneous at the 5' terminus, with transcription sites occurring at many locations between 21 and 61 bp upstream of the ATG start site of the coding region. In vitro translation experiments of the GALK1 cDNA indicate that the protein is cytosolic and not associated with the endoplasmic reticulum membrane.

Amino Acid Sequence↗
PubMed1996

An attempt on using the method of R-Q double-factor analysis to identify and group fusants.

A subsequent numeric taxonomy method for identifying and grouping the fusants was explored on the basis of characterization of the protein profiles of the fusants. By these two means, several typical excellent candidates of recombinants could be searched out quickly. Among the fusants from a definite fusion-cross, the different sister-strains were regarded as the samples of observation (n = N), the positions of the all bands of protein profiles as the objects (p = P), and the photometer-scanning area of the specific band as the experimental value (X) (zero was taken when the specific band of a certain strain was absent). The genetic multirelationships among the inter- and intra-sister-strains in terms of the positions and contents of the protein bands after fusion recombination occurred from this definite fusion-cross could therefore be determined on the same orientational factor-plate by using the computer program of the R-Q double-factor method to analyze this data matrix (Xnxp). These sister-strains could then be identified and grouped from the deduced heredity relationship between the fusants and parents.

Aspergillus niger↗
PubMed1996

[The application of expanded delto-pectoral flaps in the faciocervical region].

The delto-pectoral flap has been used to repair burned scar in the faciocervical region for some years. However, its limited size restricts its application. Furthermore, direct transfer of the flap may result in a swelling and inexpressive face and the donor site needs skin grafting. To avoid the above disadvantages, we have tried pre-expansion of the flap. In this article, the authors report the experiences in the application of the method to eighteen cases, including the surgical procedure, the applied anatomy, and typical cases as well. Also included in the article are the comparison between various therapies to the burned scar of the face, the key points for successful pre-expansion of the delto-pectoral flap, accurately maintaining the desired position. The method has been proved to have many advantages and can be widely applied.

Adolescent↗
PubMed1996

[Endoscopic control during facelifting].

The endoscopic techniques were just recently applied to aesthetic surgery. The paper reports 22 cases of video endoscopic facelift that have been performed since April 1994. The operative results were satisfactory. Clinical experience with forehead plasty, resection of corrugator and procerus muscle and other cosmetic procedures using endoscopic technique is presented.

Adult↗
PubMed1995

Comparison of the enzymatic activities of human galactokinase GALK1 and a related human galactokinase protein GK2.

The GALK1 cDNA encoding human galactokinase was recently cloned and its cognate GALK1 gene shown to be involved in galactokinase deficient galactosemia. Previously, a separate human galactokinase cDNA, GK2, was cloned by complementation of a galactokinase deficient yeast mutant; however, the galactokinase activity of GK2 was not demonstrated in mammalian cells. To compare the relative galactokinase activity of GALK1 and GK2, their corresponding cDNAs were expressed in COS cells. Northern blot analysis indicated that both cDNAs were transcribed into mRNA transcripts of the expected size; however, only the GALK1 cDNA produced high levels of galactokinase activity. This result would suggest that GALK1 is the major enzyme for galactose metabolism while the role of GK2 remains uncertain.

Base Sequence↗
PubMed1995

Characterization of an autoinhibitory domain in human mitogen-activated protein kinase-activated protein kinase 2.

Mitogen-activated protein (MAP) kinase-activated protein kinase 2, a Ser/Thr kinase, is phosphorylated and activated by MAP kinase. Sequence analysis of a clone isolated from the human HL-60 cell line revealed a 370-amino acid protein with a proline-rich N terminus, a highly conserved catalytic domain, and a C-terminal region containing a MAP kinase phosphorylation site. To better understand how the kinase is regulated, mutation analysis was used to map the functional domain(s). The wild type recombinant kinase had a low basal activity as detected by phosphorylation of a substrate peptide derived from the N terminus of glycogen synthase. Deletion of the proline-rich N terminus showed little effect on the basal activity. Deletion of the C terminus resulted in a marked increase in catalytic activity either with or without the pretreatment of the kinase by MAP kinase. Further analysis indicated that amino acid residues 339-353 in the C-terminal region were acting as an autoinhibitory domain. A synthetic peptide (RVLKEDKERWEDVK-amide) derived from this autoinhibitory domain inhibited the kinase activity in a concentration-dependent manner. These results suggest a regulatory model for the kinase.

Amino Acid Sequence↗
PubMed1995

Cloning of the galactokinase cDNA and identification of mutations in two families with cataracts.

Galactokinase is an essential enzyme for the metabolism of galactose and its deficiency causes congenital cataracts during infancy and presenile cataracts in the adult population. We have cloned the human galactokinase cDNA, which maps to chromosome 17q24, and show that the isolated cDNA expresses galactokinase activity in bacteria and mammalian cells. We also describe two different mutations in this gene in unrelated families with galactokinase deficiency and cataracts. The availability of the cloned galactokinase gene provides an important reference to identify mutations in patients with galactokinase deficiency and cataracts.

Adult↗
PubMed1995

Mouse galactokinase: isolation, characterization, and location on chromosome 11.

Elevated galactose levels can be caused by several enzyme defects, one of which is galactokinase. Galactokinase deficiency cause congenital cataracts during infancy and presenile cataracts in the adult population. We have isolated the mouse cDNA for galactokinase, which shares extensive amino acid sequence homology, 88% identity, with a recently cloned human galactokinase. It is expressed in all tissues examined. In an interspecific backcross analysis galactokinase maps to the distal region of mouse chromosome 11, a region that is homologous to human chromosome 17q22-25. The availability of the mouse gene provides an opportunity to make a knockout model for galactokinase deficiency.

Alleles↗
PubMed1995

[Anatomy and clinical application of transcervicothoracic polyphyletic blood supply skin flap].

Transcervicothoracic skin flap was used to repair the faciocervical scars left after burns in 56 cases. Anatomy and clinical application proved that the transverse cervical artery branches out a constant skin artery before it enters the trapezius muscle and this artery, after crossing the clavicle, is divided into two branches, one extending outwards, and the other downwards. The internal thoracic artery branched out an intercostal perforator on the spot 1 cm to the parasternum. The perforator extended along the intercostal plane and belonged to the direct skin artery. The rate for perforation between the second and third ribs was the highest and the diameter of the perforator the greatest. The thoracoacromial skin artery perforated through the medialsemis between the greater pectoral muscle and the deltoid muscle, and extended toward the shoulder, supplying the skin of the infraclavicular, deltoid and upper greater pectoral regions with blood. Anatomy and contrast examination showed that there are extensive anastomoses between the three groups of blood vessels. On the basis of these anastomotic branches, transregional skin flaps can be designed to repair faciocervical damages. These flaps were successfully used in the 56 cases, with 32 cases having the the branch of cervical segment of the trasverse cervical artery as the pedicle, and 24, the second and third perforators of the internal thoracic artery as the pedicle. It was proved that the transregional flaps can be successfully transferred regardless of the sites of the pedicles.

Adolescent↗
PubMed1995

[A preliminary observation of EcochG and cochlear morphology after cervical sympathectomy in guinea pigs].

In order to examine the effect of sympathetic nerve on the inner ear, we observed the changes of EcochG and ultrastructure of the hair cells before and after cervical sympathectomy in 13 guinea pigs. We also compared the results with those of the contralateral side (as a normal control group). We found that there were morphologic changes in the stereocilia of the hair cells in the surgical side. No changes were found in the thresholds, amplitudes and latencies of EcochG. It seems that the effect of the morphologic changes are too small to be detected in the electrophysiologic experiments.

Animals↗
PubMed1994

The primary structure of a human MAP kinase activated protein kinase 2.

Mitogen-activated protein (MAP) kinase is of central importance in mediating intracellular actions in response to a variety of extracellular stimuli. MAP kinase activated protein (MAPKAP) kinase 2 is one of the two known protein kinases that can be phosphorylated and activated by MAP kinase. Here we present the first complete primary structure of MAPKAP kinase 2 elucidated from a human cDNA sequence. Sequence analysis reveals that MAPKAP kinase 2 is a 370 amino acid protein containing a proline-rich N-terminal region and a well conserved catalytic domain. Northern blot analysis of MAPKAP kinase 2 showed a 4.8 kb mRNA species in HL-60 cells. In addition, we also show the first evidence that recombinant MAPKAP kinase 2 is phosphorylated and activated by MAP kinase in vitro.

Amino Acid Sequence↗