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Biomedical subjects

J Shi

Publications and source records attributed to J Shi.

At least 343 records · Page 19Linked to original sources
PubMed1993

The second dorsal metacarpal flap with vascular pedicle composed of the second dorsal metacarpal artery and the dorsal carpal branch of radial artery.

A pedicle second dorsal metacarpal flap, comprising the second dorsal metacarpal artery, the partial carpal arterial arch of the dorsal hand, and the dorsal carpal branch of radial artery, was designed. The flap may be rotated through two axes of rotation, one at the entry of carpal branch of radial artery into the first dorsal interosseous muscle and one at the entry of the recurrent cutaneous branch arising from the second dorsal metacarpal artery into the skin. The method introduced can increase as much as possible the length of the vascular pedicle of the second dorsal metacarpal flap. Thus, it can cover a small defect at a more distant area. If the width of this flap is not more than 3 cm, the donor site can be closed directly. The flap had been used in five cases with no necrosis of the flap or complication of the donor site. In further investigation of the postoperative patients, no stiffness and tightness have been observed through a short period of rehabilitation of the hand. The results are satisfactory. The anatomy, the operative technique, and three selective cases are described here.

Adult↗
PubMed1992

Cyanobacterial metallothionein gene expressed in Escherichia coli. Metal-binding properties of the expressed protein.

The recently isolated Synechococcus gene smtA encodes the only characterised prokaryotic protein designated to be a metallothionein (MT). To examine the metal-binding properties of its product the smtA gene was expressed in Escherichia coli as a carboxyterminal extension of glutathione-S-transferase. The pH of half dissociation of Zn, Cd and Cu ions from the expressed protein was determined to be 4.10, 3.50, 2.35, respectively, indicating a high affinity for these ions (in particular for Zn in comparison to mammalian MT). E. coli expressing this gene showed enhanced (ca. 3-fold) accumulation of Zn.

Amino Acid Sequence↗
PubMed1992

Expression of the pea metallothionein-like gene PsMTA in Escherichia coli and Arabidopsis thaliana and analysis of trace metal ion accumulation: implications for PsMTA function.

The PsMTA gene from pea (Pisum sativum) shares similarity with metallothionein (MT) genes and related sequences have also been isolated from a number of other higher-plant species. The proteins encoded by these genes have not yet been purified from plants and their functions remain unclear although, by analogy to MT, roles in the metabolism and detoxification of metal ions have been proposed. By contrast, correlation between transcript abundance and Fe availability has led to an alternative proposal that these genes are involved in mechanisms of Fe efficiency. Phenotypic effects of constitutive PsMTA expression were examined in Escherichia coli and Arabidopsis thaliana. Copper accumulation by E. coli cells expressing recombinant PsMTA protein was approximately 8-fold greater than in control cells. No significant effects on the accumulation of Zn or Cd were detected. In segregating A. thaliana progeny, derived from a transgenic F1 parent containing the PsMTA gene under the control of a CaMV 35S promoter, 75% of individuals accumulated more Cu (several-fold in some plants) than untransformed, control plants. These data suggest that PsMTA protein binds Cu in planta and that uncoupled (constitutive) expression of the PsMTA gene causes enhanced Cu accumulation. Roots of P. sativum plants grown under conditions of low Fe availability showed elevated activity of root surface Fe(III) reductase and accumulated more Cu than roots of plants grown in an Fe-supplemented solution. Changes in the expression of MT-like genes, coincident with changes in Fe availability, are consistent with a role in Cu homoeostasis.

Arabidopsis↗
PubMed1992

Sequence analysis of the ROB-1 beta-lactamase gene from Actinobacillus pleuropneumoniae.

The ROB-1 beta-lactamase gene from Actinobacillus pleuropneumoniae was cloned and sequenced. The structural gene encodes a 305 amino acid polypeptide. The ROB-1 beta-lactamase gene sequence is identical to that derived from Pasteurella haemolytica and only one amino acid different from that of Haemophilus influenzae, suggesting that they are derived from the same ancestor, and transformed from one to another.

Actinobacillus pleuropneumoniae↗
PubMed1992

Tyrosine-specific protein phosphorylation in response to anti-CD3 antibody is diminished in old mice.

Antiphosphotyrosine immunoblots were used to characterize phosphotyrosine-containing proteins (PY-PPNs) in anti-CD3 stimulated murine T lymphocytes. Activation led to increased phosphorylation of three PY-PPNs (MWs of 120, 80, and 40 kD) within 2 minutes, and maximal phosphoprotein levels were sustained for at least 30 min. There was a progressive decline with age in the responses of these three PY-PPNs to anti-CD3 stimulation, and some 20-23-month-old mice were virtually nonresponsive. A second group of PY-PPNs was present in unstimulated cells and not affected by anti-CD3 treatment or by age. Responses to Con A and to an antibody to the T-cell receptor were also found to be lower in old mice. Our data show that the pattern of tyrosine-specific phosphorylation in normal murine T cells is similar but not identical to patterns previously defined in murine tumor T-cell lines, and that T cells in old mice have defects in tyrosine-specific phosphorylation that could contribute to their diminished responsiveness to mitogenic stimuli.

Aging↗
PubMed1991

Expression of the pea gene PSMTA in E. coli. Metal-binding properties of the expressed protein.

The pea (Pisum sativum L.) gene PSMTA has an ORF encoding a predicted protein with sequence similarity to class I metallothioneins (MTS). To examine the metal-binding properties of the PSMTA protein it has been expressed in E. coli as a carboxyterminal extension of glutathione-S-transferase (GST). Metal ions were associated with the expressed protein when purified from lysates of E. coli grown in metal supplemented media. The pH of half-dissociation of Zn, Cd and Cu ions from the recombinant fusion protein was determined to be 5.35, 3.95 and 1.45 respectively, compared with equivalent estimates of 4.50, 3.00 and 1.80 for equine renal MT.

Amino Acid Sequence↗
PubMed1991

Decomposition of nonlinear non-Gaussian process and its application to nonlinear filter and predictor design.

An approach for decomposing of a Nonlinear Non-Gaussian Process (NNGP) is presented. A set of adjoin processes alpha's are first constructed based on the orthogonal principle so that the linear and nonlinear part of the process can be completely separated by a correlation operation without the statistical assumption on the process (i.e., it is not necessarily a Gaussian Process). The linear and nonlinear filters or predictors can then be designed and implemented independently and the consistency of parameters is guaranteed. An algorithm is given for a second order nonlinear process, and it can easily be extended to higher order cases if necessary. The method is first demonstrated by applying it to a nonlinear filter design problem, i.e., system identification. Finally, the necessity of a proposed decomposition procedure is proven by applying it to an example in which the parameters of a signal model are extracted from a version which is distorted due to the nonlinearity of the channel.

Algorithms↗
PubMed1991

Epithelial lining of sinus tracts associated with periapical disease: an immunocytochemical study using monoclonal antibodies to keratins.

We examined 30 specimens of mucosal sinus tracts arising in association with periapical inflammation. Immunocytochemistry and a panel of monoclonal antibodies to keratins were used to demonstrate the epithelial lining and its pattern of keratin expression. Half of the specimens were found to have an epithelial lining that was continuous with the mucosal epithelium and showed various degrees of extension into the sinus. The presence of an epithelial lining appeared to correlate with the duration of the sinus tracts. The immunostaining patterns of the epithelial linings were similar to those of the mucosal epithelium near the sinus opening although some differences were found. Proliferating strands of epithelium, presumably derived from the rest of Malassez, were observed deep in the tissues but were not continuous with the epithelial lining. The results suggest that the epithelial lining of sinus tracts is derived not from epithelial rests in the periapical region but from the mucosal epithelium adjacent to the opening of the sinus tract and that the observed changes in the pattern of keratinization are due to the influence of inflammation or of the connective tissue substrate.

Antibodies, Monoclonal↗
PubMed1991

A morphological study of primary pulmonary hypertension--an analysis of six autopsy cases.

Six typical autopsy cases of primary pulmonary hypertension are reported. The histopathological features were as follows: medial hypertrophy of the muscular pulmonary arteries, muscularization of arterioles, internal fibrosis and fibroelastosis of muscular pulmonary arteries with typical "onion-skin" configuration, fibrinoid necrosis of the media or necrotizing arteries of muscular pulmonary arteries, and formation of highly characteristic plexiform lesions and dilatation lesions. It is thought that the plexiform lesions seen in all six cases represent morphological changes resulting from pulmonary hypertension rather than congenital abnormalities or thromboembolism.

Adult↗
PubMed1991

[Research on the relationship between central acetylcholine and acupuncture analgesia].

The article systematically reported our physiological and biochemical work on the relationship between central acetylcholine and acupuncture analgesia. The results indicate: 1. Acupuncture on acupoints could produce analgesia. 2. Ach contents in cerebrospinal fluids and brain increased under acupuncture analgesia. 3. AChE activities iu brain elevated under acupuncture analgesia. 4. ChE inhibitor reinforced the effects of acupuncture and inhibitor of ACh synthesis could inhibit the effects of acupuncture, which could be reversed by administration of ACh and chlorocholine. M-AChR antagonists could also inhibit the effects of acupuncture. 5. The turnover rate of ACh in diencephalon, caudate nucleus and spinal dorsal horn accelerated when acupuncture analgesia. The discussion was given on the variation of metabolic dynamics in combination with related literature.

Acetylcholine↗
PubMed1990

[The change of ACh metabolism in the dorsal horn of spinal cord and spinal ganglia during electroacupuncture analgesia (EAA)].

In this paper a preliminary study was made about the relationship between ACh and the primary input of acupuncture sensation based on the changes of content of ACh, its synthetic enzyme (choline acetylase, or ChAC) and its degradation enzyme (acetylcholinesterase, or AChE) in the dorsal horn of the spinal cord and spinal ganglia. The results were found that: 1) EA at "huantiao" exerted a marked analgesia effect, the acupuncture analgesia was inhibited when the lateral dorsal root was cut off. 2) The content of ACh of the EA group were slightly lower than those of the control group. 3) AChE activity in the spinal ganglia and the dorsal horn increased markedly under electroacupuncture stimulation. 4) The activity of ChAC in the dorsal horn of rats under acupuncture stimulation was significantly higher than those of the control group. 5) ACh content in the spinal ganglia increased obviously when the degradation of peripheral ACh was inhibited by prostigmine. 6) With the lumber dorsal roots excised, AChE activity of the operative side were much lower than those of the intact side during EA stimulation. It suggest that the metabolism of ACh in the dorsal horn of the spinal cord and spinal ganglia change during the course of EAA, and only when signals produced at the acupoints are delivered to the spinal cord via ACh-containing primary somatosensory nerves, can they exert analgesic and therapeutic effect of acupuncture.

Acetylcholine↗
PubMed1990

[Electron microscopic observation on the killing of human lung carcinoma cells by lymphokine-activated killer cells (LAK cells) in vitro].

The interactions and reactions between co-cultured LAK cells and target cells were observed under scanning and transmission electron microscopy. Close contacts between these two cells were necessary to effect and sustain the killing process. In the contact area, there were prominent changes of the cell surface structures of both cells. The active motility of LAK cells accelerated the detachment and disintegration of the target cells. Lack of dense (killing) granules in the cytoplasm of LAK cells and the apoptotic death pattern of the affected target cells suggest that a non-perforin-dependent mechanism might be involved in killing. Morphologically, the killing process of LAK cells was basically similar to that of CTL and NK cells.

Adenocarcinoma↗