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J J Lin

Publications and source records attributed to J J Lin.

At least 199 records · Page 11Linked to original sources
PubMed1986

Effect of theophylline on the initiation phase of postischemic acute renal failure in rats.

These experiments were designed to test, pharmacologically, the hypothesis that adenosine mediates the reduction in glomerular filtration rate (GFR) observed during the initiation phase of postischemic acute renal failure (ARF). Six groups of pentobarbital-anesthetized rats were studied; in all groups, the left renal arteries were completely occluded for either 30 or 45 minutes, and 30 minutes after relieving the occlusion, two consecutive 40-minute clearances were begun. Two control groups received no pretreatment; two experimental groups were pretreated with intravenous theophylline (24 mumol/kg prime followed by 0.28 mumol/min/kg infusion); two further experimental groups were pretreated with a higher dose of theophylline (111 mumol/kg prime followed by 1.1 mumol/min/kg infusion). As assessed by reduction in inulin clearance, the impairment of GFR was directly related to the duration of ischemia. The lower dose of theophylline had no significant effects on inulin clearances of right or left kidneys in either group (previously ischemic for 30 or 45 minutes). The higher dose of theophylline also had no significant effects on right kidney inulin clearances, but it significantly increased the inulin clearances of left kidneys previously ischemic for 30 to 45 minutes. This theophylline-induced increase in inulin clearance after 30 minutes of ischemia was accompanied by an increase in renal plasma flow. Because theophylline is a competitive antagonist at adenosine receptors, these results are consistent with the hypothesis that endogenous adenosine mediates, at least in part, the hemodynamic changes in postischemic ARF in rats.

Acute Kidney Injury↗
PubMed1985

Tropomyosin isoforms in chicken embryo fibroblasts: purification, characterization, and changes in Rous sarcoma virus-transformed cells.

Seven polypeptides (a, b, c, 1, 2, 3a, and 3b) have been previously identified as tropomyosin isoforms in chicken embryo fibroblasts (CEF) (Lin, J. J.-C., Matsumura, F., and Yamashiro-Matsumura, S., 1984, J. Cell. Biol., 98:116-127). Spots a and c had identical mobility on two-dimensional gels with the slow-migrating and fast-migrating components, respectively, of chicken gizzard tropomyosin. However, the remaining isoforms of CEF tropomyosin were distinct from chicken skeletal and cardiac tropomyosins on two-dimensional gels. The mixture of CEF tropomyosin has been isolated by the combination of Triton/glycerol extraction of monolayer cells, heat treatment, and ammonium sulfate fractionation. The yield of tropomyosin was estimated to be 1.4% of total CEF proteins. The identical set of tropomyosin isoforms could be found in the antitropomyosin immunoprecipitates after the cell-free translation products of total poly(A)+ RNAs isolated from CEF cells. This suggested that at least seven mRNAs coding for these tropomyosin isoforms existed in the cell. Purified tropomyosins (particularly 1, 2, and 3) showed different actin-binding abilities in the presence of 100 mM KCl and no divalent cation. Under this condition, the binding of tropomyosin 3 (3a + 3b) to actin filaments was significantly weaker than that of tropomyosin 1 or 2. CEF tropomyosin 1, and probably 3, could be cross-linked to form homodimers by treatment with 5,5'-dithiobis-(2-nitrobenzoate), whereas tropomyosin a and c formed a heterodimer. These dimer species may reflect the in vivo assembly of tropomyosin isoforms, since dimer formation occurred not only with purified tropomyosin but also with microfilament-associated tropomyosin. The expression of these tropomyosin isoforms in Rous sarcoma virus-transformed CEF cells has also been investigated. In agreement with the previous report by Hendricks and Weintraub (Proc. Natl. Acad. Sci. USA., 78:5633-5637), we found that major tropomyosin 1 was greatly reduced in transformed cells. We have also found that the relative amounts of tropomyosin 3a and 3b were increased in both the total cell lysate and the microfilament fraction of transformed cells. Because of the different actin-binding properties observed for CEF tropomyosins, changes in the expression of these isoforms may, in part, be responsible for the reduction of actin cables and the alteration of cell shape found in transformed cells.

Animals↗
PubMed1985

Monoclonal antibodies against chicken tropomyosin isoforms: production, characterization, and application.

Eight mouse monoclonal antibodies, CH1, CH106, CH291, CL2, CG1, CG3, CG beta 2 and CG beta 6, against chicken tropomyosin isoforms have been prepared and characterized. The antigens recognized by these isoform-specific monoclonal antibodies were identified by both solid-phase radioimmunoassay and protein immunoblotting. To some extent, most antibodies showed isoform-specific, but one (CG3) recognized all isoforms of tropomyosin from chicken materials. The effects of monoclonal antibodies on the binding of cardiac tropomyosin to F-actin were investigated. Antibodies CH1, CH106, and CH291 had the ability to interfere with the binding of tropomyosin to F-actin, whereas others appeared to have no effect. Monoclonal antibody CL2 was able to distinguish the skeletal muscle tropomyosin-enriched microfilaments from the fibroblastic tropomyosin-enriched microfilaments of differentiating muscle cells. This antibody will be most useful for studying the compartmentalization of microfilaments and microfilament-associated proteins, particularly actin and tropomyosin isoforms during muscle differentiation. Immunofluorescence microscopy with CG1 antibody which recognized CEF tropomyosin isoforms 1 and 3 revealed the continuous staining of stress fibers in some populations of CEF cells. On the other hand, both periodic fluorescent staining and continuous staining of stress fibers were observed with CG3 antibody in all CEF cells.

Actin Cytoskeleton↗
PubMed1984

Weldability of beta titanium arch wires.

Beta titanium arch wire segments were joined in a variety of configurations by means of four different commercial welders available to the orthodontist. Test specimens were prepared using the point-to-point and flat-to-flat electrode configurations and a range of settings on each welding apparatus. Tension-shear and tension-twist tests were conducted to determine force values to rupture the welded joints; 90 degrees cold-bend tests provided a measure of relative ductility near the joints compared to the as-received wires. Results indicated that the flat-to-flat electrode configuration is preferred for obtaining strong welded joints with low levels of distortion. Optimum settings have been determined for each of the four welders. Microstructural observations of the beta titanium and joint structure are presented; these are correlated with the energy level settings for the welding process.

Dental Alloys↗
PubMed1984

Intraplaque hemorrhage: its significance in cerebrovascular disease.

Recently, carotid plaque factors, specifically intraplaque hemorrhage, have been studied with respect to the production of cerebrovascular symptoms. Ninety-five carotid endarterectomies were performed and the plaques that were removed were examined for intraplaque hemorrhage. Patients were separated into three groups: those with specific neurologic symptoms, those with nonlateralizing symptoms, and those who were asymptomatic. In the group of patients who presented with specific neurologic symptoms, correlation was made between the age of the intraplaque hemorrhage and the timing of symptoms. The vast majority of patients with specific neurologic symptoms exhibited carotid plaque hemorrhage, but patients with nonlateralizing symptoms and those who were asymptomatic also demonstrated an unexpectedly high percentage of intraplaque hemorrhage. Moreover, our results show a poor relationship between the timing of symptoms and the age of the intraplaque hemorrhage. These data do not refute the concept that intraplaque hemorrhage may play a role in the production of cerebrovascular symptoms, but they do refute the notion that the mere presence of hemorrhage causes specific neurologic symptoms and they also refute the previous report that demonstrates a good correlation between the timing of symptoms and the age of the intraplaque hemorrhage.

Aged↗
PubMed1984

Tropomyosin-enriched and alpha-actinin-enriched microfilaments isolated from chicken embryo fibroblasts by monoclonal antibodies.

Antitropomyosin and anti-alpha-actinin monoclonal antibodies have been used to isolate two classes of microfilaments, i.e., tropomyosin-enriched and alpha-actinin-enriched microfilaments, respectively, from cultured chicken embryo fibroblasts. Electron microscopic studies of the isolated tropomyosin-enriched microfilaments showed periodic localization of tropomyosin along the microfilaments, with a 35-nm repeat. On the contrary, the isolated alpha-actinin-enriched microfilaments showed no obvious periodicity. Many individual alpha-actinin-enriched microfilaments with length greater than 1 micron (ranging from 1 to 10 microns) were aggregated by anti-alpha-actinin monoclonal antibodies. Both of the isolated microfilaments had the ability to activate the Mg2+-ATPase activity of skeletal muscle myosin, although different extents of activation were observed. These two classes of microfilaments also differed in their protein composition. Molar ratios of major identifiable proteins in the isolated microfilaments were alpha-actinin(dimer):actin(monomer):tropomyosin(dimer) = less than 0.02:8.06:1.00 for tropomyosin-enriched microfilaments and 0.44:13.91:1.00 for alpha-actinin-enriched microfilaments. By two-dimensional gel analysis of the isolated microfilaments, we have found seven spots which possess typical tropomyosin properties including pI 4.5, immunological cross-reaction, lack of proline and tryptophan, and heat stability. Pulse-chase experiments suggested that the assembly of microfilament-associated proteins, at least for alpha-actinin and tropomyosins, was coordinately regulated by the assembly of actin into microfilaments.

Actinin↗
PubMed1984

Ability of Pollen to Germinate prior to Anthesis and Effect of Desiccation on Germination.

The ability of pollen to germinate prior to anthesis was tested using Easter lily (Lilium longiflorum L.) and corn (Zea mays L.). Lily pollen normally dries to a low moisture content between anthesis and pollination while corn does not. The corn pollen germinated well (about 73%) when removed from anthers 1 day before anthesis and placed on culture medium. The lily pollen germinated poorly (0 to 5%) when harvested one to six days before anthesis. However, the lily pollen harvested one or two days before anthesis gave greatly improved germination (about 55%) after it was dried to a low moisture content. The results indicate that an internal control prevents premature germination of lily pollen and that drying is the final stage of pollen maturation. A different sort of regulatory mechanism must operate to prevent premature germination of corn pollen.

Journal Article↗
PubMed1983

Differential expression of tropomyosin forms in the microfilaments isolated from normal and transformed rat cultured cells.

Using a newly developed method for microfilament isolation (Matsumura, F., Yamashiro-Matsumura, S. and Lin, J. J.-C. (1983) J. Biol. Chem. 258, 6636-6644), we have analyzed protein composition of microfilaments in "normal" and transformed rat tissue culture cells. They include REF-52 (an established rat embryo cell line) cells, REF-52 transformed by DNA viruses (SV40 or adenovirus type 5), normal rat kidney cells, and normal rat kidney cells transformed by RNA viruses (Kirsten or Rous sarcoma virus). Microfilaments from normal rat culture cells contain three major tropomyosins (apparent Mr = 40,000, 36,500, and 32,400) and two relatively minor tropomyosins (apparent Mr = 35,000 and 32,000). In transformed cells the levels of one or two of the major tropomyosins (Mr = 40,000 and 36,500) are decreased and the levels of one or both of the minor tropomyosins (Mr = 35,000 and 32,000) are increased. These changes in tropomyosin patterns were also observed in temperature shift experiments with rat-1 cells transformed with a Rous sarcoma virus mutant, temperature-sensitive for transformation. Cell-free translation of whole cell mRNA generated similar tropomyosin patterns on two-dimensional gels, suggesting that changes in the pattern of tropomyosin expression were largely effected at the level of RNA rather than by post-translational modification. Such changes in the tropomyosin composition of microfilaments were consistently found to accompany the various morphological alterations associated with transformation. We suggest that alterations in the pattern of tropomyosin expression are involved in, or cause, rearrangement of stress fibers and that this may be responsible (in part) for morphological transformation.

Adenoviruses, Human↗
PubMed1983

Biochemical characterization of the mammalian stress proteins and identification of two stress proteins as glucose- and Ca2+-ionophore-regulated proteins.

Biochemical properties of the heat shock or stress proteins of mammalian cells have been investigated using two-dimensional gel electrophoresis and immunological techniques. Of the major mammalian stress proteins (Mr = 72,000, 73,000, and 90,000) and minor stress proteins (Mr = 80,000, 100,000, and 110,000), the 80- and 90-kDa proteins were found to be phosphoproteins in all cell types examined. The 100-kDa protein was found to incorporate phosphate in only some cell types examined. In studies of the metabolic incorporation of mannose into the stress proteins, only the 100-kDa protein was found to be a glycoprotein. Two of the stress proteins, the 80- and 100-kDa species, were found to be identical with the proteins induced in cells grown in the absence of glucose (i.e. the "glucose-regulated proteins"). These same two proteins also were induced in cells treated with the calcium ionophore A23187. To begin examining the intracellular location of these multiregulated proteins, immunofluorescence microscopy studies were carried out using a monoclonal antibody against the 100-kDa stress protein. The antigen was localized primarily with the Golgi apparatus and less prominently with the plasma membrane and nucleus. Heat shock treatment resulted in an increased number of the cells exhibiting a nuclear location of 100 kDa.

Animals↗
PubMed1983

Isolation and characterization of tropomyosin-containing microfilaments from cultured cells.

We have developed a new method for the rapid isolation of tropomyosin-containing microfilaments from cultured cells using anti-tropomyosin monoclonal antibodies. Anti-tropomyosin monoclonal antibodies induce the bundle formation of microfilaments, which can be easily collected by low speed centrifugation. Electron microscopic studies of the isolated microfilaments show periodic localization of tropomyosin along the microfilaments of nonmuscle cells with a 33-34 nm repeat. Furthermore, the isolated microfilaments have the ability to activate the Mg2+-ATPase activity of skeletal muscle myosin to almost the same extent as skeletal muscle F-actin (filamentous actin). This microfilament isolation method is applicable to a variety of cell types, including REF-52 cells (an established rat embryo line), L6 myoblasts, 3T3 fibroblasts, Chinese hamster ovary cells, baby hamster kidney (BHK-21) cells, mouse neuroblastoma cells, gerbil fibroma cells, and chicken embryo fibroblasts. Sodium dodecyl sulfate-polyacrylamide gel analysis shows that, in addition to actin, microfilaments isolated from REF-52 cells contain five species of tropomyosin with apparent Mr = 40,000, 36,500, 35,000, 32,400, and 32,000, alpha-actinin, and as yet unknown proteins with apparent Mr = 83,000 and 37,000. The molar ratio of total tropomyosin (dimer) to actin in the isolated microfilaments is 1:8. The patterns of these multiple forms of tropomyosin were found to change when REF-52 cells were transformed with SV40 or adenovirus type 5.

Actins↗
PubMed1983

Ovarian carcinoma metastatic to breast.

We have described a case of ovarian carcinoma with bilateral breast involvement. In patients with a previous history of carcinoma who have a breast tumor, metastatic disease must be considered and the histologic features of the tumors compared. Therapy is focused on the primary site, though local treatment may be necessary. The presence of metastatic breast involvement generally indicates widespread metastases, and the prognosis is poor.

Antineoplastic Agents↗
PubMed1983

Upper and lower airway disease in penicillamine treated patients with rheumatoid arthritis.

Four of 133 patients with rheumatoid arthritis suddenly developed progressive respiratory symptoms while receiving penicillamine therapy. None had previous disease. None of 89 patients treated with gold alone and 0 of 380 not taking gold or penicillamine developed respiratory symptoms. Two of the 4 developed simultaneous severe, unresponsive sinusitis. Lung biopsy demonstrated obliterative bronchiolitis (OB) in 2 patients, fibrosing alveolitis in one. A clinical course characteristic of OB was noted in the 4th patient. Sinus biopsy in 2 demonstrated lymphocytic and plasmacytic mucosal infiltration. The high frequency of OB in penicillamine treated patients and its absence in 469 non penicillamine treated patients suggests the possibility of a causal relationship.

Arthritis, Rheumatoid↗
PubMed1982

A monoclonal antibody that recognizes Golgi-associated protein of cultured fibroblast cells.

We have obtained a hybridoma clone, JLJ5a, which secretes monospecific antibody directed against a 110-kdalton protein of gerbil fibroma cells, Rat-1 fibroblasts, and L6 myoblasts. It appears to be localized in the Golgi apparatus by the following criteria: (a) In double-staining experiments the localization of the 110-kdalton protein by the JLJ5a monoclonal antibody was coincident with the reaction products of thiamine pyrophosphatase (one of the enzyme markers of the Golgi apparatus; Novikoff and Goldfischer, 1961, Proc. Natl. Acad. Sci. U.S.A. 47:802-810) in the same cells. (b) The staining pattern of the JLJ5a monoclonal antibody became fragmented and dispersed into vacuoles after pretreatment of the cells with Colcemid or monensin.

Animals↗