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Biomedical subjects

C L Wang

Publications and source records attributed to C L Wang.

At least 127 records · Page 7Linked to original sources
PubMed1995

The center of ground reaction force during lifting.

The center locations of the ground reaction force were estimated when subjects assumed upright and bending postures as well as when they lifted at low and high speeds. Ten subjects participated in this study and were instructed to assume two postures and to perform two liftings sequentially in a random order. The center locations of the ground reaction force were calculated using a Computerized Dyno Graphic system (INFOTRONIC). The center of the ground reaction force in the full bending posture had a more anterior location than it did in the upright standing posture. When measured during the lifting activity, the center of the ground reaction force shifted forward and then backward during the whole activity. The center location shifted to a more anterior location during high-speed lifting than it did during low-speed lifting.

Adult↗
PubMed1995

[A comparison of compression stockings of different pressures with lower leg edema in spinal cord injury or lesions patients].

We tested 80 spinal cord injury or lesion patients admitted to Department of Rehabilitation Medicine of Chang Gung Memorial hospital from Jan, 1994 to Aug, 1994, in order to assess the effectiveness of compression stockings of different pressures. The study group consisted of patients who, after leaving bed for 4 hours, had a volume change in the lower extremities greater than 50 c.c., as measured by a specially designed water bucket. One of the lower limb was used as the control group and the other limb was used as the experimental group. Different stocking compression pressure, 12 mmHg 20 mmHg, and 30 mmHg, were used for the experimental limb. No placebo stocking was used in the control group. Change in the lower limb volume and degree of comfort after leaving bed for 4 hours were measured. The experimental results reveal that wearing stocking with compression pressure, 12 mmHg, 20 mmHg, 30 mmHg, had therapeutic effects (P < 0.01). The therapeutic effects of the 12 mmHg stocking was less than the 20 mmHg and 30 mmHg stocking. There was no significant difference between the therapeutic effects of the 20 mmHg and 30 mmHg stocking. As for the degree of comfort, 12 mmHg was better than 20 mmHg, and 20 mmHg better than 30 mmHg. When choosing the type of compression stocking to treat lower leg edema in spinal cord injury or lesion patients, we suggest starting with 20 mmHg compression pressure stockings would be a better choice, as they are cheaper, more comfortable to wear and can provide the same therapeutic effects as 30 mmHg compression stockings.

Adult↗
PubMed1994

Troponin I encompasses an extended troponin C in the Ca(2+)-bound complex: a small-angle X-ray and neutron scattering study.

We have studied the solution structure of skeletal muscle troponin C complexed with troponin I in the presence of calcium using small-angle X-ray and neutron scattering. 4Ca2+.troponin C in the complex has an extended dumbbell shape with a radius of gyration of 23.9 +/- 0.5 A and a maximum linear dimension of approximately 72 A, similar to the values obtained from the crystal structure coordinates of troponin C (Herzberg & James, 1985). Troponin I is even more extended than troponin C with a radius of gyration of 41 +/- 2 A and a maximum linear dimension of approximately 118 A. The centers-of-mass for each component of the complex are approximately coincident (< 10-A separation) as are their long axes, and the troponin I component encompasses the 4Ca2+.troponin C. These data provide new insights into the nature of the conformational arrangement of this important Ca(2+)-sensitive molecular switch.

Calcium↗
PubMed1994

Myosin S1 changes the orientation of caldesmon on actin.

Changes in the orientation of caldesmon bound to actin in skeletal ghost myofibrils caused by the binding of myosin subfragment 1 (S1) were measured by fluorescence-detected linear dichroism using fluorescence microscopy. Gizzard caldesmon, labeled with acrylodan at its two Cys residues (CaD*), bound to actin with a probe angle that was unaffected by actin-bound tropomyosin. Irrigation of fibrils with myosin S1 dissociated most of the bound CaD*, but reintroduction of CaD* resulted in its rebinding to actin, without dissociation of S1, with a 7 degrees difference in probe angle. A similar change in probe angle was also observed when a 27-kDa actin-binding C-terminal fragment of caldesmon, labeled with acrylodan at its single Cys 580 (CaD-27*), was used. Introducing MgADP, which bound to S1 in the CaD*-actin-S1 ternary complex in the fibril, reversed the bound CaD* dichroism. These results indicate that (i) myosin heads and caldesmon compete for a common actin binding site; (ii) a ternary complex of CaD*-actin-S1 can be formed with an orientation of CaD* different from that in the CaD*-actin binary complex, and (iii) MgADP, which binds to and reorients myosin S1, affects the orientation of CaD* in the ternary complex. These results are consistent with a two-state binding model of caldesmon for actin in which state 1 involves a site that is competitive with S1 binding and state 2 involves a site that is formed in the presence of bound S1.

Actins↗
PubMed1994

Neuroblastoma cell-mediated leukocyte chemotaxis: lineage-specific differentiation of interleukin-8 expression.

To determine whether neural crest-derived neuroblastoma cells may release cytokines which regulate the function of leukocytes, we found that neuroblastoma (HTB-11) cells did not constitutionally express IL-1 beta, TNF alpha, or IL-8 mRNA. However, TNF alpha, which induced HTB-11 cells to differentiate to perineurium-like cells, induced expression of IL-8 mRNA in a dose- and time-dependent fashion. In contrast, pentoxifylline (1 mM), which promoted HTB-11 cells to differentiate to polygonal neuron-like cells, did not induce IL-8 mRNA expression. As determined by enzyme-linked immunoassay, high levels of IL-8 were detectable in the culture supernatants from TNF alpha-treated neuroblastoma cells, but not pentoxifylline-treated neuroblastoma cells (19.60 +/- 2.34 vs 0.10 +/- 0.06 ng/ml). Culture supernatants obtained from TNF alpha-treated neuroblastoma cells induced chemotaxis of neutrophils and lymphocytes that was significantly blocked by anti-IL-8 neutralizing antibodies. Detection of a leukocyte chemotactic factor was not observed in the culture supernatants from pentoxifylline-treated cells. These results suggest that neural crest-derived perineurium-like cells, but not neuron-like cells, may release a leukocyte chemotactic factor or factors such as IL-8 which could be involved in leukocyte recruitment seen in inflammatory diseases affecting peripheral nerves.

Cell Communication↗
PubMed1994

Monoclonal antibody FDC-6 exhibits binding to human plasma fibronectin: a caveat for cervicovaginal oncofetal fibronectin testing?

OBJECTIVE: Monoclonal antibody FDC-6 has been used clinically to measure cervicovaginal fibronectin and to predict patients at risk for preterm labor. Because bleeding is often a complicating factor during pregnancy, the aim of this study was to determine whether FDC-6 reactive fibronectin is present in normal human plasma. STUDY DESIGN: Quantitative Western immunoblots and a commercially available enzyme-linked immunosorbent assay were used to measure FDC-6 binding to nonpregnant human and bovine plasma fibronectin. FDC-6 binding to whole sera was also assessed, as was the effect of enzymatic deglycosylation of human plasma fibronectin. RESULTS: Both assays demonstrated measurable FDC-6-reactive fibronectin in nonpregnant human blood, with plasma concentrations ranging from 3 to 12 micrograms/ml (1% to 4% of total plasma fibronectin). FDC-6 had no detectable binding activity to bovine plasma fibronectin. De-O-glycosylated human plasma fibronectin had markedly reduced binding activity for FDC-6. CONCLUSIONS: FDC-6 binds specifically to a clinically significant percentage of circulating O-glycosylated human plasma fibronectin isoforms that are not associated with pregnancy. This caveat should be considered when pregnant patients are evaluated for the presence of FDC-6 reactive oncofetal fibronectin in the cervix or vagina.

Animals↗
PubMed1994

Gene synthesis and functional expression of a protein exhibiting monodomain IgG Fc binding.

A gene encoding a bacterial IgG Fc binding domain was designed and synthesized. The synthetic DNA fragment was cloned 3' to an inducible trpE promoter such that expression of the gene in Escherichia coli produced abundant Fc binding protein fused to the first seven amino acids of the trpE protein. The recombinant protein contained a single Fc binding domain and demonstrated efficient binding to human IgG in Western blot analysis. This protein degraded rapidly following cell lysis in the absence of protease inhibitors, but could be effectively protected by the addition of protease inhibitor. After purification of the protein by IgG affinity chromatography, IgG Fc binding ability was retained for at least 24 h at either 23 or 37 degrees C and on heating for 15 min at temperatures up to 65 degrees C. No immunoprecipitation was observed in interactions between the monodomain Fc binding protein and IgG molecules. Unlike staphylococcal protein A, no detectable binding of the monodomain IgG Fc binding protein was observed to either IgM or IgA. Truncated proteins, expressed from a series of 3' deletions of the synthetic gene, were used to estimate the minimum portion of a monodomain Fc binding protein that retained Fc binding ability.

Amino Acid Sequence↗
PubMed1994

A single Fc binding domain--alkaline phosphatase gene fusion expresses a protein with both IgG binding ability and alkaline phosphatase enzymatic activity.

A recombinant gene fusion was created and cloned using a previously constructed gene encoding a monodomain IgG Fc binding protein and the gene coding for bacterial alkaline phosphatase. The construct was able to express and secrete a fusion protein that exhibited both IgG binding and alkaline phosphatase enzymatic activities. Greater than 60% of the protein demonstrating both biological activities was detected from periplasmic space preparations. Nanogram concentrations of the Fc binding--alkaline phosphatase fusion protein allowed primary IgG antibody detection without the use of conjugated secondary antibodies. Removal of the domain coding for alkaline phosphatase resulted in decreased resistance of the protein to proteolytic degradation and the loss of IgG Fc binding ability. Using affinity-purified fusion protein, the specificity of binding to IgG, IgM and IgA was examined; binding was strong to IgG and barely detectable against IgM or IgA. Affinity for binding of the fusion protein to IgG (Kd = 6.7 x 10(-8) M) was determined to be equal to or greater than previously reported for protein A.

Alkaline Phosphatase↗
PubMed1994

Transforming growth factor-beta stimulates trophoblast oncofetal fibronectin synthesis in vitro: implications for trophoblast implantation in vivo.

In pregnancy tissues, oncofetal fibronectin (onfFN) has been localized specifically to the extracellular matrix (ECM) surrounding extravillous anchoring trophoblasts of the placental-uterine junction and chorion. When isolated from first or third trimester placentas, human cytotrophoblasts in culture secrete and deposit onfFN in the ECM. In addition, onfFN synthesis is significantly up-regulated in response to serum stimulatory factor(s). The goal of this study was to examine the role of transforming growth factor-beta (TGF beta), a cytokine present in uterine decidua, as a stimulator of trophoblast onfFN production. Our initial insight into the significance of TGF beta resulted from the serendipitous use of cord serum from a neonate with severe alloimmune thrombocytopenia. Trophoblasts cultured in medium containing this serum underwent normal morphological differentiation, but produced markedly less onfFN. In an analogous fashion, trophoblasts cultured in normal serum preincubated with anti-TGF beta neutralizing antibodies also produced significantly less onfFN. Exogenously added TGF beta 1 restored the ability of trophoblasts to produce onfFN by a factor of 4- to 5-fold in medium containing thrombocytopenic serum. In platelet-poor serum derived from human or bovine plasma, TGF beta 1 also induced onfFN synthesis, as assayed both in the conditioned medium and by immunocytochemical localization of onfFN in cell-associated ECM fibrils. Dose-response analysis demonstrated that the onfFN stimulatory response is sensitive to TGF beta, with an ED50 of 0.1-0.2 ng/ml. In a reciprocal fashion, TGF beta inhibited beta hCG secretion 3- to 4-fold. Our results demonstrate that TGF beta is a significant stimulator of trophoblast onfFN production. Furthermore, TGF beta appears to modulate trophoblast differentiation by up-regulating the expression of an anchoring trophoblast marker (onfFN) and down-regulating a phenotypic marker of villous syncytiotrophoblast (hCG beta). We speculate that trophoblast responsiveness to TGF beta in the implantation milieu contributes to trophoblast adhesion by stimulating the production of a trophoblast-derived implantation site fibronectin.

Antigens, Neoplasm↗
PubMed1994

Predictors for wound healing in ischemic lower limb amputation.

Determination of the level of amputation of an ischemic lower limb presents a difficult problem. This prospective study evaluated parameter capable of predicting wound healing in patients with peripheral vascular disease. Forty-four amputations performed on 38 patients for advanced ischemia of a lower extremity were analyzed. Among them, 20 patients had diabetes mellitus and 10 received vascular reconstruction prior to the amputation. All patients except one had a skin temperature measurement and 26 patients had segmental blood pressure measurements before amputation. Of the 44 amputations, 31 healed successfully and 13 failed to heal without further intervention. Patients who had an amputation above the ankle joint had a significantly better outcome than those who had amputation below the ankle joint. Among the amputations proximal to the ankle joint, all patients with segmental blood pressures > 70 mmHg at the amputation level had successful wound healing, compared with only half of those patients with segmental pressures < 70 mmHg. However, ankle segmental pressure was not associated with the outcome of wound healing in the amputations distal to the ankle joint. The absolute skin temperature and the difference between the skin and ambient temperature were found to be poor predictors for wound healing. No significant differences were detected among the successes and failures with regard to the patient's sex, age, blood chemistry and duration of diabetes mellitus.

Adult↗
PubMed1994

[Experimental studies on changes in retinal enzyme activities under acute ocular hypertension in cat eyes].

The changes of 10 enzymatic activities of cat retinas and their blood vessels under acute ocular hypertension were systematically observed by enzyme histochemical methods. These changes were induced by the damage caused by retinal ischemia-reperfusion. The activities of the free radical scavengers, catalase and hydrogen peroxidase, were decreased, demonstrating that the excess of free radicals is one of the essential causes of the injury. The principles of treatment are besides lowering of intraocular hypertension, during retinal ischemic stage, oxygen and nutrients needed urgently should be supplied through extra-vascular route and during reperfusion stage, free radical scavengers ought to be given.

Animals↗
PubMed1993

Electron microscopic images suggest both ends of caldesmon interact with actin filaments.

An improved rotary shadowing technique enabled us to visualize chicken gizzard caldesmon (CaD) and its complexes with one or two covalently linked calmodulin (CaM) molecules by electron microscopy. Using a monoclonal antibody against an epitope in the N-terminal region of CaD (anti-N), we can now identify the end of the molecule that is involved in binding to another protein molecule. Thus in the 1:1 complex of CaD and CaM, the CaM molecule was almost always associated with the C-terminus of CaD, indicating preferential CaM-binding to the C-terminal region. We have also studied binding of CaD to filamentous actin (F-actin), using an EM technique that avoids spraying or freeze drying and thereby preserves the structure of F-actin. Only one end of CaD appeared to bind to F-actin, leaving the rest of the molecule projecting away from the filament. While the majority of anti-N bound at the free end of CaD, some antibody molecules were found on F-actin. These findings suggest that either end of CaD can bind to F-actin. Experiments using a monoclonal antibody against the C-terminus of CaD (anti-C) supported this idea. When the native thin filaments that contain endogenous CaD were incubated with anti-N, almost all the bound antibodies were found on the filaments, indicating that the N-terminal regions of CaD interact with actin, and that the binding affinity of the N-terminal region of CaD for actin is higher in vivo than that in vitro, either because the properties of CaD have been altered during purification, or because of the presence of some other component(s) associated with the native filaments.

Actins↗
PubMed1993

Benign persistent pneumoperitoneum in systemic sclerosis.

We describe a 50-year-old Chinese woman who had severe gastrointestinal manifestations from systemic sclerosis complicated by spontaneous pneumoperitoneum in the absence of either visceral perforation or pneumatosis cystoides intestinalis. This is a rare complication of systemic sclerosis; only four other cases have been reported. Recognition of this condition is important so as to avoid unnecessary surgery.

Female↗
PubMed1992

Regulation of vascular smooth muscle tone by caldesmon.

Caldesmon is an actin-binding protein present in smooth muscle cells that also inhibits actin-activated myosin ATPase activity. To assess the possible role of caldesmon in the regulation of smooth contraction, we investigated the effects of synthetic peptides on force directly recorded from single hyperpermeable smooth muscle cells of ferret aorta and portal vein. GS17C, a peptide that contains the residues from Gly651 to Ser667 of the caldesmon sequence plus an added cysteine at the C terminus, binds calmodulin in a Ca(2+)-dependent manner and also binds to F-actin but does not inhibit actomyosin ATPase activity (Zhan, Q., Wong, S.S., and Wang, C.-L.A. (1991) J. Biol. Chem. 266, 21810-21814). In cells in which Ca2+ was clamped at pCa 7.0, GS17C induced a dose-dependent contraction (EC50 = 0.92 microM) in aorta cells, whereas it evoked little or no contraction in portal vein cells. The GS17C-induced contraction in aorta cells was inhibited at higher Ca2+ concentrations (above pCa 6.6) and by pretreatment with calmodulin. Another peptide, C16AA, which contains the residues from Ala594 to Ala609 and does not bind actin or calmodulin, did not induce contraction. Our results strongly suggest that GS17C induces contraction by the displacement of the inhibitory region of endogenous caldesmon and, furthermore, that caldesmon present in these smooth muscle cells regulates contraction by providing a basal resting inhibition of vascular tone.

Actins↗
PubMed1992

Antibacterials. synthesis and structure-activity studies of 3-aryl-2-oxooxazolidines. 4. Multiply-substituted aryl derivatives.

The synthesis and structure-activity relationship (SAR) studies of the effect of different polysubstitution patterns in the aromatic ring of 5-(acetamidomethyl)oxazolidinone antibacterials (I) on antibacterial activity are presented. Compounds I were prepared by the six-step synthesis described previously (Gregory, W. A.; et al. J. Med. Chem. [formula: see text] 1989, 32, 1673), electrophilic aromatic substitution reactions of 3-substituted compounds, and functional-group interchange reactions of 3,4-disubstituted compounds. Antibacterial evaluation of compounds I against Staphylococcus aureus and Enterococcus faecalis gave the following results. The 2,4- and 2,5-disubstituted derivatives have weak or no antibacterial activity. Antibacterial activities of 3,4-disubstituted compounds are comparable to those of the 4-monosubstituted analogues for small 3-substituents (smaller than Br), but decline rapidly for larger 3-substituents. 3,4-Annulated derivatives are comparable in activity to their open-chain analogues. 3,5-Disubstituted and 3,4,5- and 2,4,6-trisubstituted derivatives are devoid of antibacterial activity.

Anti-Bacterial Agents↗
PubMed1992

Deletion derivatives of pAgK84 and their use in the analysis of Agrobacterium plasmid functions.

The 47.7-kb plasmid pAgK84, present in Agrobacterium radiobacter strain K84, confers production of a novel, highly specific, antiagrobacterial antibiotic called agrocin 84. Strain K84 is used commercially to biocontrol crown gall caused by agrocin 84-susceptible strains of Agrobacterium tumefaciens. Efficient biocontrol is dependent upon production of agrocin 84 by strain K84. Starting with a derivative of pAgK84 containing a Tn5 insertion, a series of deletion derivatives of the plasmid were isolated. The smallest of these, pJS500, contains about 8 kb of the original agrocin plasmid and localized the replication functions to between 4 and 6 o'clock on the physical map. A smaller derivative, produced by clonal rescue of a Tn5 insertion in the 4 o'clock region, further localized the minimal replication functions to a 1.5-kb region mapping between coordinates 18.1 and 19.6. Analysis of plasmid stability indicated that functions required for maintenance of the plasmid under nonselective conditions are tightly linked to the minimal replication region. This region also encodes incompatibility functions; the deletion derivatives were all incompatible with the wild-type pAgK84. The stability/replication locus of pAgK84 maps just anticlockwise from the Tra region. This region is retained fully in pAgK1026, the directed Tra- derivative of pAgK84 which is now in use as the primary crown gall biocontrol agent in Australia. One of the deletion derivatives, the 15-kb pJS400, was used as a vector to clone the KpnI fragments of an octopine-type Ti plasmid. Traits known to be encoded on these fragments were expressed and properly regulated in Agrobacterium hosts. One clone, encoding the Ti plasmid replication/incompatibility region, was used to cure IncRh1 Ti plasmids from their hosts. This clone also was found to be incompatible with pAtK84b, a large plasmid encoding opine catabolism present in A. radiobacter strain K84. This indicates that the opine catabolic plasmid is closely related to the IncRh1 Ti plasmids.

Adenine Nucleotides↗
PubMed1992

A dynamic study of the ankle-foot complex.

A kinematic study of the ankle-foot complex in 19 healthy volunteers was performed using computerized radiocinematography. We found that the instant centers of rotation of the ankle joint fell closely within the talus in the sagittal plane. When the ankle joint moved, the talus, the calcaneus and the navicular bone performed different excursions. Except for the movement in the sagittal plane, the calcaneus assumed eversion in dorsiflexion and inversion in plantar flexion when the ankle moved in an open kinematic chain (under non-weight-bearing conditions). In a closed kinetic chain movement (under weight-bearing conditions), the lower leg exhibited internal rotation, and the talus moved plantarward when the ankle was dorsiflexed. The internal rotation of the lower leg did not cause a slippery rotation of the foot on the surface, but rather it was converted into eversion of the calcaneus in the frontal plane.

Adolescent↗