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S H Liu

Publications and source records attributed to S H Liu.

At least 163 records · Page 9Linked to original sources
PubMed1989

Studies on the contracture of the mouse diaphragm induced by sodium selenite.

In this study, we found that sodium selenite was potent in inducing contracture of the mouse diaphragm. The possible mechanism of action of selenite was investigated. Contracture was induced by a direct action of selenite on the muscle membrane rather than that selenite enhanced transmitter release from the motor nerve terminals, since denervation, d-tubocurarine and tetrodotoxin did not inhibit the selenite-induced contracture. Although selenite decreased both the membrane potential and the amplitude of the muscle action potential, neither high K+ nor glycerol treatment, which closed the transverse tubule, reduced the selenite-induced contracture, suggesting that depolarization of the muscle membrane was not essential for the induction of the contracture. EGTA (1-50 mM) inhibited the selenite-induced contracture in a concentration-dependent manner. In contrast, varying the external Ca2+ concentrations from 10(-3) to 10 mM or raising Mg2+ concentration to 10 mM did not affect the contracture. Similarly, the contracture induced by caffeine was not affected by lowering the external Ca2+ concentration to 10(-3) mM but was completely inhibited by 30 mM EGTA. Selenite pretreatment markedly potentiated the caffeine contracture and prolonged treatment with caffeine inhibited the selenite contracture. All of these findings suggest that the selenite contracture was not dependent on external Ca2+ but was induced by the release of Ca2+ from internal membranes such as the sarcoplasmic reticulum. Pretreatment with trypsin, glutathione or cyanide blocked the selenite-evoked contracture. Therefore, we postulate that the selenite-induced contracture was induced by the initial binding of selenite to the sulfhydryl groups of the muscle membrane, which then triggered the release of Ca2+ from internal membranes such as the sarcoplasmic reticulum.

Animals↗
PubMed1989

Regulation of the human beta-actin promoter by upstream and intron domains.

We have identified three regulatory domains of the complex human beta-actin gene promoter. They span a region of about 3000 bases, from not more than -2011 bases upstream of the mRNA cap site to within the 5' intron (832 bases long). A distal upstream domain contains at least one enhancer-like element. A proximal upstream domain, with a CArG [for CC(A + T rich)6GG] motif found in all known mammalian actin genes, seems to confer serum, but not growth factor, inducibility. The third domain is within the evolutionarily conserved 3' region of the first intron and contains a 13 base-pair sequence, identical to the upstream sequence with the CArG motif. This domain also contains sequences that are both serum and fibroblast growth factor inducible.

Actins↗
PubMed1989

Effects of sodium selenite on neuromuscular junction of the mouse phrenic nerve-diaphragm preparation.

The effects of sodium selenite on the neuromuscular junction of the phrenic nerve-diaphragm of the mouse were studied. Nerve-evoked twitches of the diaphragm of the mouse, the frequency of miniature endplate potentials, the quantal content of endplate potentials and the compound action potentials of the axon were measured. Sodium selenite induced a slight increase of the amplitude of the twitch, followed by twitch depression. The amplitude of the twitch, increased by selenite, became more prominent after the suppression of the twitch induced by cadmium ions, d-tubocurarine or magnesium ions. It appeared that the increased amplitude of twitch was due to the facilitation of transmitter release, since selenite significantly increased the frequency of miniature endplate potentials, and the amplitude and quantal content of endplate potentials; the amplitude and half decay time of miniature endplate potentials were unaffected. Twitch depression induced by selenite was enhanced by ammonium ions, high potassium and low magnesium and attenuated by high calcium. During the period of gradual depression of the twitch, selenite decreased the amplitude of compound action potentials of the phrenic nerve axon and caused the disappearance of endplate potentials. Ammonium ions enhanced the blockade of axonal conduction induced by selenite. Moreover, the depolarizing agents, ammonium and high potassium also induced an initial increase of twitch amplitude followed by depression of the twitch. These findings indicate that selenite probably alters the release of the transmitter by depolarizing the nerve membrane. The effects of selenite were antagonized by glutathione and cyanide, suggesting that the binding of selenite to sulfhydryl groups of the membrane was essential for inducing its pharmacological actions.

Animals↗
PubMed1989

Medial gastrocnemius hematoma mimicking deep vein thrombosis: report of a case.

Tennis leg, strain of the medial head of the gastrocnemius muscle, may follow a trivial trauma in athletic and nonathletic activities. Complete or partial tears of the musculotendinous unit may result in a hematoma. Clinical manifestations of gastrocnemius hematoma in a 64-year-old man with local swelling, pain and tenderness that was aggravated by passive dorsiflexion of the ankle joint, mimicked deep vein thrombosis. Failure to appreciate the precedent trivial trauma and the localized swelling and ecchymosis led to delayed diagnosis and inappropriate heparinization. The definite diagnosis was established by CT scan which revealed a local soft tissue mass within the gastrocnemius consistent with a hematoma. A compartment syndrome developed the day after heparinization and was adequately treated by discontinuation of heparin, aspiration and rest. Differentiation between tennis leg and deep vein thrombosis is of paramount importance, since the etiology, treatment and prognosis of these two clinical entities are quite different. Venography is recommended as specifically diagnostic for deep vein thrombosis while CT scan for gastrocnemius hematoma.

Diagnosis, Differential↗
PubMed1988

Primary structure of the mouse laminin B2 chain and comparison with laminin B1.

One of the major components of basement membranes is the glycoprotein laminin, made up of three disulfide-bonded subunits, the A, B1, and B2 chains. We have isolated and sequenced overlapping mouse laminin B2 chain cDNA clones covering 7562 base pairs. The deduced amino acid sequence predicts that the mature B2 chain consists of 1572 residues, has an unglycosylated molecular weight of 173,541, and possesses 14 potential N-linked glycosylation sites. Analysis of the predicted secondary structure shows the presence of six domains, two rich in alpha-helical structure, two composed of homologous cysteine-rich repeat units, and two globular regions. The organization of the molecule is very similar to that of the mouse laminin B1 chain, and significant sequence homology between the B1 and B2 chains was found in their two cysteine-rich domains and in their amino-terminal globular domains.

Amino Acid Sequence↗
PubMed1988

Educational needs in patient care practices in Hong Kong.

We conducted a survey on staff perceptions of what the educational needs would be for an infection surveillance and control program in patient care practices in 10 hospitals in Hong Kong. Seven hundred twenty nurses were interviewed and were requested to select their needs from six topics: isolation procedures, disinfection of environment and instruments, surgical wound care, urinary catheter care, prevention of hospital-acquired pneumonia, and prevention of infusion therapy sepsis. According to their pattern of needs, the clinical units could be divided into three groups. Staff members in the "medically oriented units," consisting of the medical, geriatric, obstetric, and intensive care units, indicated that their greatest needs were in the areas of isolation procedures and disinfection of environment and instruments, whereas nurses in the "surgically oriented units," consisting of surgical, orthopedic, and gynecologic units, indicated that surgical wound care was the area where education was most needed. The pattern in the third group, the pediatric units, was similar to that of medical units in indicating isolation procedures and disinfection of environment and instruments as the greatest needs but differed in having a higher score for prevention of hospital-acquired pneumonias and a lower score for surgical wound care. An effective educational program should take these needs into consideration. We discuss the application of the survey findings in planning in-service education in infection control.

Cross Infection↗
PubMed1988

Amino acid sequence and domain structure of entactin. Homology with epidermal growth factor precursor and low density lipoprotein receptor.

Entactin (nidogen), a 150-kD sulfated glycoprotein, is a major component of basement membranes and forms a highly stable noncovalent complex with laminin. The complete amino acid sequence of mouse entactin has been derived from sequencing of cDNA clones. The 5.9-kb cDNA contains a 3,735-bp open reading frame followed by a 3'-untranslated region of 2.2 kb. The open reading frame encodes a 1,245-residue polypeptide with an unglycosylated Mr of 136,500, a 28-residue signal peptide, two Asn-linked glycosylation sites, and two potential Ca2+-binding sites. Analysis of the deduced amino acid sequence predicts that the molecule consists of two globular domains of 70 and 36 kD separated by a cysteine-rich domain of 28 kD. The COOH-terminal globular domain shows homology to the EGF precursor and the low density lipoprotein receptor. Entactin contains six EGF-type cysteine-rich repeat units and one copy of a cysteine-repeat motif found in thyroglobulin. The Arg-Gly-Asp cell recognition sequence is present in one of the EGF-type repeats, and a synthetic peptide from the putative cell-binding site of entactin was found to promote the attachment of mouse mammary tumor cells.

Amino Acid Sequence↗
PubMed1988

Effects of electroacupuncture and gonadotropin-releasing hormone treatments on hormonal changes in anoestrous sows.

The therapeutic effects of acupuncture in treating reproductive disturbances of man and animals have been proven in the past and is used clinically already. However, the mechanism of such therapy is not known yet. In this study, anoestrous sows were used to investigate the mechanism. Anoestrous sows with luteal ovaries were allocated to three groups. Four sows received electroacupuncture treatment at Pai-Hui and Wei-Ken (acupuncture treated group; group 1). Three sows received electroacupuncture treatment at Chiang-Feng and Chou-Shu (acupuncture control group; group 2). Four received 50 micrograms of gonadotropin-releasing hormone (GnRH) intravenously (drug control group; group 3). The concentrations of luteinizing hormone, progesterone, oestradiol and cortisol in serum were measured by radioimmunoassay. Oestrus return was monitored during 14 days after treatment. At the end of this observation period, the number of animals returned to oestrus were 3, 1 and 1 in groups 1, 2 and 3, respectively. It suggests that only treatment with acupuncture at Pai-Hui and Wei-Ken had therapeutic effects in inducing oestrus. This finding is further supported by the changes of serum sex hormone concentrations. Serum LH concentrations decreased for about 2 hours after electro-acupuncture treatment both in groups 1 and 2, whereas those in group 3 increased sharply at 10 minutes, reached to a peak at 20 minutes and returned gradually to basal level between 4 and 6 hours after GnRH injection. Serum progesterone concentrations rose between 4 to 6 hours after treatment in groups 1 and 3 but not in group 2. Five sows become oestrus, showed a decreased progesterone level 2 days after treatments whereas the other six anoestrous sows did not. Oestradiol levels did not have meaningful changes during the blood sampling period of 5 to 7 days in these 3 groups. Cortisol levels elevated in 15 minutes after the electroacupuncture in groups 1 and 2. However, the increment of cortisol induced by the electroacupuncture was less than that induced by the first bleeding, indicating that the adrenal stimulation may not be the main reason of the therapeutic action. The results indicated that the electroacupuncture treatment and GnRH injection could alter the release of LH from the pituitary in different ways but only electroacupuncture at Pai-Hui and Wei-Ken has a specific action on ovary and a significant therapeutic effect. Therapeutic effects of electroacupuncture on reproductive disturbance may involve a synergism of somatic-ovary and uterus reflex and central nervous-endocrine system (the hypothalamo-pituitary-ovary axis).

Acupuncture Therapy↗
PubMed1987

Experimental autoimmune dacryoadenitis. I. Lacrimal gland disease in the rat.

Experimental autoimmune dacryoadenitis was produced in Lewis rats by immunization with a single intradermal administration of a 3M KCl extract of exorbital lacrimal gland in CFA, when enhanced by simultaneous i.v. injection of killed Bordetella pertussis. No significant lacrimal lesions were observed in control animals immunized with the extracts of Harderian or salivary glands. Gel filtration of the 3M KCl extract on Sephacryl S-300 column yielded three protein fractions. Only fraction III (MW = 10-55K) induced marked dacryoadenitis following a single injection of 2.0 mg protein in CFA plus pertussis. The infiltrates in the exorbital lacrimal lesions were first apparent around the ducts and associated vasculature. From this area, the infiltrates appeared to spread to the acini drained by these ducts, ultimately involving as much as 30-50% of the gland. The affected glands most commonly showed a diffuse nongranulomatous infiltrate of small lymphocytes, macrophages, and plasma cells; this was focal in nature, involving acinar atrophy and breakdown, and replaced the normal architecture in extreme cases. The Harderian and salivary glands were uninvolved in these animals, suggesting a restricted specificity of this response. Lewis rats immunized with exorbital lacrimal gland fractions I or II in CFA plus pertussis showed only minimal lesions, similar to controls receiving CFA and pertussis without antigen. These findings suggest that an autoantigen exists in the lacrimal gland of the rat that is capable of inducing a specific lymphoproliferative dacryoadenitis.

Animals↗
PubMed1987

Experimental autoimmune dacryoadenitis. II. Harderian gland disease in the rat.

Experimental autoimmune dacryoadenitis was induced in 100% of Lewis rats by immunization with a KCl extract of Harderian gland in complete Freund's adjuvant (CFA), providing that the animals had received simultaneously i.v. injection of killed Bordetella pertussis. No significant pathological changes in the Harderian gland were observed in control animals immunized with KCl extracts of lacrimal or salivary glands. Gel filtration of the KCl extract on Sephacryl S-300 column yielded three protein fractions. Fraction II (MW = 50-100K) induced severe Harderian gland disease following a single injection of 2.0 mg protein in CFA plus pertussis. The initial lesions consisted of multiple focal infiltrates of mononuclear cells. Later, the inflammatory process assumed a more granulomatous form, with significant contribution by epithelioid and giant cells. In contrast, Lewis rats immunized with Harderian gland fractions I or III proteins, or with extracts of lacrimal or salivary gland, showed little or no inflammatory lesions. These data suggest that Harderian gland contains unique tissue-specific autoantigen(s) capable of inducing autoimmune granulomatous dacryoadenitis in the rat.

Animals↗
PubMed1986

Experimental immunogenic granuloma of the orbit: transfer of granulomatous hypersensitivity with a subset of T lymphocytes.

An experimental model to investigate orbital granuloma formation in inbred rats was established. Animals sensitized to trinitrophenyl ovalbumin (TNP-OA) and challenged retro-orbitally with TNP-OA covalently linked o Sepharose 4B beads specifically developed a granulomatous response. This granulomatous reactivity was passively transferred into normal animals by lymph node cells, but not by serum antibody from sensitized donors. Lymphocytes which transfer granuloma formation in normal recipients were characterized by cell fractionation and membrane marker analysis. These experiments show that the effector cells capable of transferring granulomatous hypersensitivity are enriched in the lower density fractions on discontinuous Percoll gradients. These cells are lymphoblasts and express the W3/25 helper T lymphocyte marker. It was also demonstrated that lymphoid cells from sensitized donors in the higher density Percoll fraction appear to be incapable of adoptively transferring granulomatous responsiveness directly to normal recipients. However, incubation of these high density lymphocytes with specific antigen resulted in marked enhancement of their ability to transfer the disease. Antigen-induced activation also resulted in an increase in both lymphoblasts and the W3/25 marker. The authors conclude, therefore, that a subset of T cells which are lymphoblasts and express the helper-cell marker is responsible for granuloma formation in sensitized animals and is capable of transferring orbital granuloma formation to non-sensitized normal recipients.

Animals↗