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S Lin

Publications and source records attributed to S Lin.

At least 433 records · Page 24Linked to original sources
PubMed1996

[Teprenone in the treatment of chronic superficial gastritis, a multicentre study].

Teprenone (Selbex), a gastric mucosal protective drug for treatment of chronic gastritis and gastric ulcer, has recently been used in the People's Republic of China. Teprenone in the treatment of chronic superficial gastritis (CSG): a surveillance study was recently conducted in 4 major hospitals in Beijing. The study included 98 patients (teprenone group 53 patients, Merzulene-S group 45 patients) with endoscopically proven gastritis. The study showed that teprenone may relieve symptoms of CSG in 8 weeks. The effectiveness rate for flatulence was 90.9% and for epigastralgia 87.2%. The improvement rate for the chronic inflammation in histopathology was 39.6% and disappearance rate for the activity of inflammation was 13.9%. It raised significantly the aminohexose level in gastric mucosa (P < 0.05) and increased gastric mucosal blood flow in gastric antrum (P < 0.05). These data suggest that teprenone is a safe and effective gastric mucosal protective drug.

Adolescent↗
PubMed1996

[Effects of intermittent short-course chemotherapy under full-course supervision on the treatment of smear positive pulmonary tuberculosis].

OBJECTIVE: To evaluate the effects of intermittent short-course chemotherapy under full-course supervision on the treatment of smear positive pulmonary tuberculosis. METHOD: The regimens of 2H3R3Z3S3(E3)/4H3R3 and 2H3R3Z3S3E3/6H3R3E3 were respectively used in 125 initial and 249 relapse smear positive pulmonary tuberculosis cases under full-course supervision and management. RESULTS: The total rate of treatment completion was 99.7%, and the rates of sputum negative conversion in initial and relapse cases were 96.7% and 84.8% respectively. During three-year follow-up, the bacteriological relapse rates were found to be 1.8% in initial cases and 10.2% in relapse cases. CONCLUSIONS: The regimen was proved to be convenient, economical and effective in tuberculosis control programme.

Antitubercular Agents↗
PubMed1996

The second space experiment of protein crystallization with domestic facilities.

The second experiment of protein crystallization was performed on domestic re-entry satellite FSW-2 in 1994-07. The results are superior to the ones of the first mission in 1992: 9 of 10 different proteins were crystallized in space, and 70% of the total 48 samples yielded single crystals. Besides hen egg-white lysozyme which grew high-quality crystals on the first mission, an acidic phospholipase A2(aPLA2) from snake venom and hemoglobin from Anser Indicus produced good-quality crystals suitable for X-ray diffraction analyses. The positive effect of microgravity on protein crystal growth is verified again at this time.

Aerospace Medicine↗
PubMed1996

Prostate-specific membrane antigen: a novel folate hydrolase in human prostatic carcinoma cells.

A novel monoclonal antibody has been developed that reacts strongly with human prostatic cancer, especially tumors of high grade. This antibody (7E11C-5) is currently in Phase 3 trials as an imaging agent for metastatic disease. We have cloned the gene that encodes the antigen that is recognized by the 7E11C-5 monoclonal antibody and have designated this unique protein prostate-specific membrane (PSM) antigen. PSM antigen is a putative class II transmembranous glycoprotein exhibiting a molecular size of Mr 94,000. Functionally, class II membrane proteins serve as transport or binding proteins or have hydrolytic activity. Preliminary studies have demonstrated binding of pteroylmonoglutamate (folate) to membrane fractions that also cross-reacted with the PSM monoclonal antibody. We observed substantial carboxypeptidase activity as folate hydrolase associated with PSM antigen. The purpose of our study was to demonstrate that human prostatic carcinoma cells expressing PSM antigen exhibit folate hydrolase activity using methotrexate triglutamate (MTXGlu3) and pteroylpentaglutamate (PteGlu5) as substrates. Isolated membrane fractions from four human prostate cancer cell lines (LNCaP, PC-3, TSU-Prl, and Duke-145) were examined for folate hydrolase activity using capillary electrophoresis. After timed incubations at various pH ranges and in the presence and absence of thiol reagents, separation of pteroyl(glutamate)n derivatives was achieved with an electrolyte of sodium borate and SDS, while absorbance was monitored at 300 nm. The results demonstrate clearly that LNCaP cells, which highly express PSM, hydrolyze gamma-glutamyl linkages of MTXGlu3. The membrane-bound enzyme is an exopeptidase, because it progressively liberates glutamates from MTXGlu3 and PteGlu5 with accumulation of MTX and PteGlu1, respectively. The semipurified enzyme has a broad activity from pH 2.5 to 9.5 and exhibits activity maxima at pH 5 and 8. Enzymatic activity is maintained in the presence of reduced glutathione, homocysteine, and p-hydroxymercuribenzoate (0.05-0.5 mm) but was inhibited weakly by DTT (>/=0.2 mm). By contrast to LNCaP cell membranes, membranes isolated from other human prostate adenocarcinoma cells (PC-3, Duke-145, and TSU-Pr1) did not exhibit comparable hydrolase activity, nor did they react with 7E11-C5 monoclonal antibody. After transfection of PC-3 cells with a full-length 2.65-kb PSM cDNA subcloned into a pREP7 eukaryotic expression vector, non-PSM antigen-expressing PC-3 cells developed immunoreactivity to 7E11-C5 monoclonal antibody and demonstrated folate hydrolase activities and optimum pH activity profiles identical to those of LNCaP cells. The membrane-bound enzymes from both LNCaP- and PC-3-transfected cells also have a capacity to hydrolyze an alpha-linked glutamyl moiety from N-acetyl-alpha-aspartylglutamate. We have identified that PSM antigen is a pteroyl poly-gamma-glutamyl carboxypeptidase (folate hydrolase) and is expressed strongly in human prostate cancer. Cancer cells that express this enzyme are resistant to methotrexate therapy. Those developing future therapeutic strategies in the treatment of prostate cancer that utilize folate antagonists need to consider this mechanism of resistance.

Antigens, Surface↗
PubMed1995

Fluorescent labeling of purified beta 2 adrenergic receptor. Evidence for ligand-specific conformational changes.

The purpose of the present study was to develop an approach to directly monitor structural changes in a G protein-coupled receptor in response to drug binding. Purified human beta 2 adrenergic receptor was covalently labeled with the cysteine-reactive, fluorescent probe N,N'-dimethyl-N-(iodoacetyl)-N'-(7-nitrobenz-2-oxa-1,3-diazol-4- yl)ethylenediamine (IANBD). IANBD is characterized by a fluorescence which is highly sensitive to the polarity of its environment. We found that the full agonist, isoproterenol, elicited a stereoselective and dose-dependent decrease in fluorescence from IANBD-labeled beta 2 receptor. The change in fluorescence could be plotted against the concentration of isoproterenol as a simple hyperbolic binding isotherm demonstrating interaction with a single binding site in the receptor. The ability of several adrenergic antagonists to reverse the response confirmed that this binding site is identical to the well described binding site in the beta 2 receptor. Comparison of the response to isoproterenol with a series of adrenergic agonists, having different biological efficacies, revealed a linear correlation between biological efficacy and the change in fluorescence. This suggests that the agonist-mediated decrease in fluorescence from IANBD-labeled beta 2 receptor is due to the same conformational change as involved in receptor activation and G protein coupling. In contrast to agonists, negative antagonists induced a small but significant increase in base-line fluorescence. Despite the small amplitude of this response, it supports the notion that antagonists by themselves may alter receptor structure. In conclusion, our data provide the first direct evidence for ligand-specific conformational changes occurring in a G protein-coupled receptor. Furthermore, the data demonstrate the potential of fluorescence spectroscopy as a tool for further delineating the molecular mechanisms of drug action at G protein-coupled receptors.

Adrenergic beta-Agonists↗
PubMed1995

Secondary electron transfer processes in membranes of Heliobacillus mobilis.

Picosecond transient absorption difference spectroscopic experiments were performed on membranes of the antenna/reaction center complex of Heliobacillus mobilis to study the electron transfer processes. Particular emphasis was placed on the blue spectral region, where the difference spectra of iron-sulfur centers and quinones are significantly different. Spectra were measured at room temperature in the wavelength region from 400 to 470 nm and from 630 to 730 nm. Laser excitation was into the 788 nm Q gamma band of the bacteriochlorophyll g of the reaction center complex. Global analysis in both wavelength regions reveals three kinetic components. A 25 ps phase originates from the decay of the excited state of antenna to form the primary charge-separated state P798+A0-; a 600 ps component is assigned to the electron transfer from the primary electron acceptor A0 to a secondary electron acceptor; a nondecaying component on the time scale measured represents the formation of the secondary charge-separated state. When the secondary electron acceptors were reduced by adding dithionite at pH 11, the 600 ps component disappeared. Only a 25 ps component and a constant were observed in the 630-730 nm region. The 25 ps component is assigned to the excitation decay in the antenna and the formation of P798+A0-, just as in the nonreduced sample. In the reduced sample, the P798+A0- state does not decay on the time scale measured. In the 400-470 nm region, the same kinetic behavior was observed. The absorption difference spectra of the primary and the secondary electron acceptor were constructed from different charge-separated states.(ABSTRACT TRUNCATED AT 250 WORDS)

Bacteria↗
PubMed1995

Structure-reactivity relationships for beta-galactosidase (Escherichia coli, lac Z). 1. Brønsted parameters for cleavage of alkyl beta-D-galactopyranosides.

Seven substituted alkyl beta-D-galactopyranosides 1-OR have been prepared and shown to be fair to excellent substrates for hydrolysis catalyzed by beta-galactosidase (Escherichia coli, lac Z). Brønsted parameters of (beta 1g)k3 = -0.49 +/- 0.13 and (beta 1g)kcat/Km = -0.75 +/- 0.14, respectively, were determined at pH 8.6 for k3 (s-1), the first-order rate constant for cleavage of enzyme-bound 1-OR, and kcat/Km (M-1 s-1), the second-order rate constant for reaction of the free enzyme and 1-OR. There is a weak correlation between log Km and the pKa of the alkyl alcohol leaving group, which is attributed to stabilization of the Michaelis complex by hydrophobic interactions between the enzyme and electron-withdrawing halogen substituents at the alkoxy leaving group. These binding interactions are probably both productive and expressed in the value of kcat/Km and nonproductive and expressed in the value of k3. The negative values of beta 1g are inconsistent with enzymatic catalysis of endocyclic cleavage of the glycosidic bond. The values of beta 1g for enzyme-catalyzed cleavage of alkyl beta-D-galactopyranosides lie between those observed for the spontaneous (beta 1g approximately -1.25) and specific-acid-catalyzed (beta 1g approximately 0) cleavage of acetals, and these pathways are therefore excluded for the enzyme-catalyzed reaction. Removal of the metal cofactor Mg2+ from the enzyme causes a approximately 0.2 unit decrease in (beta 1g)k3 for beta-galactosidase-catalyzed cleavage of 1-OR. The interpretation of this change in beta 1g is unclear. The Brønsted coefficients for the beta-galactosidase-catalyzed reaction are consistent with participation by an essential catalytic residue in concerted general-acid catalysis of cleavage of the glycosidic bond of 1-OR and/or stabilization of developing negative charge at the alkoxy oxygen by interaction with the magnesium ion cofactor.

Binding Sites↗
PubMed1995

Structure-reactivity relationships for beta-galactosidase (Escherichia coli, lac Z). 2. Reactions of the galactosyl-enzyme intermediate with alcohols and azide ion.

Velocities for the synthesis of beta-D-galactopyranosyl derivatives by transfer of the galactosyl group from beta-galactosidase to seven alkyl alcohols, glucose, and azide ion have been determined as the difference in the velocities for beta-galactosidase-catalyzed cleavage of 4-nitrophenyl beta-D-galactopyranoside to give 4-nitrophenoxide anion (v PNP) and hydrolysis of this compound to give D-galactose (v Gal). Rate constant ratios kROH/ks (M-1) for partitioning of the galactosylated enzyme between reaction with alkyl alcohols and solvent determined by this method are in good agreement with values of kROH/ks (M-1) determined by analysis of alcohol inhibition of enzyme-catalyzed hydrolysis of the corresponding alkyl beta-D-galactopyranosides. Absolute rate constants kROH (M-1 s-1) for reaction of alkyl alcohols with the galactosylated enzyme intermediate were calculated from the corresponding rate constant ratio kROH/ks (M-1) and ks = 710 s-1. A Brønsted parameter of (beta nuc) ROH = -0.19 +/- 0.10 was determined from the second-order rate constants for the reactions of alcohols with the galactosylated enzyme. The large difference between (beta 1g)kcat/Km = -0.75 +/- 0.14 for cleavage of alkyl beta-D-galactopyranosides to form the galactosylated enzyme and (beta nuc)ROH = -0.19 for the reverse synthesis reaction requires that the equilibrium constants for galactosyl group transfer from alkyl beta-D-galactopyranosides to the enzyme increase sharply with decreasing pKa of the alkyl alcohol leaving group. These data give beta eq = -0.56 +/- 0.05 for the reaction of alkyl beta-D-galactopyranosides with ethanol to form ethyl beta-D-galactopyranoside and alkyl alcohol. Several effects that lead to this increased ease of cleavage of alkyl beta-D-galactopyranosides with decreasing basicity of the alkoxy group are discussed. A second-order rate constant of kGlc = 1.2 x 10(4) M-1 s-1 was determined for reaction of glucose with the galactosylated enzyme. The relatively low reactivity of glucose is surprising, because an earlier observation that the galactosylated enzyme complex generated by the cleavage of lactose undergoes release of glucose and synthesis of allolactose at nearly equal rates suggests that the binding of glucose to the galactosylated enzyme should be partly irreversible and that it takes place near the encounter-controlled limit. The data suggest a significant stabilization of nonproductive complexes formed by binding of glucose to the galactosylated enzyme. beta-Galactosidase catalyzes the hydrolysis of beta-D-galactopyranosyl azide, but not the synthesis of this compound by reaction of azide ion with the galactosylated enzyme.(ABSTRACT TRUNCATED AT 400 WORDS)

Alcohols↗
PubMed1995

Reconstitution of interactions between tyrosine kinases and the high affinity IgE receptor which are controlled by receptor clustering.

High affinity IgE receptor (Fc epsilon RI) signaling after contact with antigen occurs in response to receptor clustering. This paper describes methodology, based on vaccinia virus driven protein expression, for probing signaling pathways and its application to Fc epsilon RI interactions with the lyn and syk tyrosine kinases. Reconstitution of the complete tetrameric Fc epsilon RI receptor, lyn and syk in a non-hematopoietic 'null' cell line is sufficient to reconstruct clustering-controlled receptor tyrosine phosphorylation and activation of syk, without apparent requirement for hematopoietic specific phosphatases. The src family kinase lyn phosphorylates Fc epsilon RI in response to receptor clustering, resulting in syk binding to the phosphorylated Fc epsilon RI. Lyn also participates in the tyrosine phosphorylation and activation of syk in a manner which is dependent on phosphorylated Fc epsilon RI. Using overexpression of active and dominant negative syk proteins in a mast cell line which naturally expresses Fc epsilon RI, we corroborate syk's role downstream of receptor phosphorylation, and demonstrate that syk SH2 domains protect receptor ITAMs from ongoing dephosphorylation. Based on these results, we propose that receptor clustering controls lyn-mediated Fc epsilon RI tyrosine phosphorylation by shifting a balance between phosphorylation and dephosphorylation towards accumulation of tyrosine phosphorylated Fc epsilon RI. Fc epsilon RI tyrosine phosphorylation functions to bring syk into a microenvironment where it becomes tyrosine phosphorylated and activated, thereby allowing clustering to indirectly control syk activity.

3T3 Cells↗
PubMed1995

Potent inhibitors of the HIV-1 protease with good oral bioavailabilities.

A series of novel pseudo-symmetrical and unsymmetrical inhibitors based on the backbone modification of a peptidomimetic were synthesized and found to be highly potent inhibitors of the HIV-1 protease (IC50 = 2.9 to < 0.5 nM). These compounds also possess good antiviral activity in vitro as measured by inhibition of the cytopathic effect of HIV-1(3B) in MT-4 lymphocytes. Importantly, some of these compounds also have good oral bioavailabilities in rats (F = 30.6% to 100%). One of these compounds 4C, also has good oral bioavailability in beagle dogs and cynomolgus monkeys.

Animals↗
PubMed1995

Weekly oral etoposide in patients with Kaposi's sarcoma associated with human immunodeficiency virus infection: a phase I multicenter trial of the AIDS Clinical Trials Group.

We conducted a Phase I trial to evaluate the safety, maximally tolerated dose (MTD), antitumor activity, and pharmacology of once-weekly oral etoposide in patients with Kaposi's sarcoma (KS) and AIDS. From September 1990 to October 1991, 27 eligible patients with biopsy-confirmed KS were treated at six etoposide dose levels, ranging from 150 to 400 mg weekly. Patients were treated until their tumor progressed or until unacceptable toxicity developed. On the first day of therapy, etoposide plasma concentrations were measured by high-performance liquid chromatography. The MTD was defined as the etoposide dose that induced reversible grade 3 toxicity in three of six patients during the first 4 weeks. Although dose-limiting toxicity was uncommon during the first 4 weeks of treatment (three of 27 patients), and the MTD was not reached, with longer treatment > 50% of patients developed dose-limiting toxicities, most commonly neutropenia. Responses were observed at all dosage levels (except 350 mg weekly), with partial tumor regression documented in nine (36%) of 25 evaluable patients. There was marked variability in etoposide area under the plasma concentration versus time curve, elimination half-time (t1/2), and urinary excretion. These pharmacokinetic features were not, however, associated with the presence of gastrointestinal symptoms, the severity of side effects, or tumor response. We conclude that weekly oral etoposide can be safely administered to patients with AIDS and KS. The observed antitumor effects over a wide range of doses support further studies with very low and minimally toxic etoposide doses, alone or in combination with other agents.

Acquired Immunodeficiency Syndrome↗
PubMed1995

Ultrafast energy transfer in light-harvesting chlorosomes from the green sulfur bacterium Chlorobium tepidum.

Two independent pump-probe techniques were used to study the antenna energy transfer kinetics of intact chlorosomes from the green sulfur bacterium Chlorobium tepidum with femtosecond resolution. The isotropic kinetics revealed by one-color experiments in the BChl c antenna were inhomogeneous with respect to wavelength. Multiexponential analyses of the photobleaching/stimulated emission (PB/SE) decay profiles typically yielded (apart from a approximately 10 fs component that may stem from the initial coherent oscillation) components with lifetimes 1-2 ps and several tens of ps. The largest amplitudes for the latter component occur at 810 nm, the longest wavelength studied. Analyses of most two-color pump-probe profiles with the probe wavelength red-shifted from the pump wavelength yielded no PB/SE rise components. PB/SE components with approximately 1 ps risetime were found in 790 --> 810 and 790 --> 820 nm profiles, in which the probe wavelength is situated well into the BChl a absorption region. A 760 --> 740 nm uphill two-color experiment yielded a PB/SE component with 4-6 ps risetime. Broadband absorption difference spectra of chlorosomes excited at 720 nm (in the blue edge of the 746 nm BChl c Qy band) exhibit approximately 15 nm red-shifting of the PB/SE peak wavelength during the first several hundred fs. Analogous spectra excited at 760 nm (at the red edge) show little dynamic spectral shifting. Our results suggest that inhomogeneous broadening and spectral equilibration play a larger role in the early BChl c antenna kinetics in chlorosomes from C. tepidum than in those from C. aurantiacus, a system studied previously. As in C. aurantiacus, the initial one-color anisotropies r(0) for most BChl c wavelengths are close to 0.4. The corresponding residual anisotropies r(infinity) are typically 0.19-0.25, which is much lower than found in C. aurantiacus (> or = 0.35); the transition moment organization is appreciably less collinear in the BChl c antenna of C. tepidum. However, the final one-color anisotropies at 789 and 801 nm are approximately 0 and 0.09 respectively, and the final anisotropy in time 780 --> 800 nm experiment is approximately -0.1. These facts indicate that the BChI a transition moments themselves exhibit some order, and are directed at an angle > 54.7 degrees on the average from the BChl c moments. The one-color profiles exhibit coherent oscillations at most wavelengths, including 800 nm; Fourier analyses of these oscillations frequently yield components with frequencies 70-80 and 130-140 cm-1.

Anisotropy↗
PubMed1995

Catalytic and immunologic characterization of hepatic and lung cytochromes P450 in the polar bear.

The Arctic Ocean is subject to considerable influx of anthropogenic pollutants including halogenated organic compounds. The polar bear (Ursus maritimus) is at the top of the arctic marine food web and is an ideal species for monitoring the level and distribution of contaminants in the arctic ecosystem. As the first step in the development of a biological method for assessing the functional exposure of polar bears to xenobiotics, biochemical studies were undertaken to characterize polar bear cytochromes P450. Liver and lung samples were obtained in the field from four, freshly killed, adult, male polar bears and immediately frozen at -196 degrees. Microsomes were subsequently prepared and used for the measurement of total cytochrome P450 content and aminopyrine N-demethylase, benzphetamine N-demethylase, ethylmorphine N-demethylase, p-nitrophenol hydroxylase and testosterone hydroxylase activities. Immunoblots containing hepatic and lung microsomal samples from the polar bears were probed using antibodies generated against several purified rat cytochrome P450 isozymes. Monoclonal antibody to rat cytochrome P450 1A1 and polyclonal antibodies to rat cytochromes P450 1A1, 2B1 and 3A1, as well as antibody to epoxide hydrolase, cross-reacted to varying degrees with polar bear hepatic microsomes. In addition, polyspecific antibody to the rat cytochrome P450 2C subfamily gave several immunostained protein bands, but antibodies specific to rat cytochrome P450 2C7 and 2C13 did not react, while antibody specific to cytochrome P450 2C11 yielded an ambiguous result. Except for anticytochrome P450 2B1 and polyspecific antibody to the cytochrome P450 2C subfamily, the antibodies listed above did not cross-react with polar bear lung microsomes at the protein concentrations used. The results demonstrate that polar bear liver contains multiple forms of cytochrome P450 that are catalytically active toward diverse substrates and that several of these forms are immunochemically related to rat cytochrome P450 isozymes. Immunochemical homologues of rat cytochrome P450 1A, 2B, 2C and 3A subfamilies, and of rat epoxide hydrolase are present in polar bear liver. In addition, the polar bears all had high levels of immunoreactive cytochrome P450 1A and 2B proteins, probably as a consequence of induction by environmental contaminants.

Animals↗
PubMed1995

Restoring the apoptosis suppression response to IL-5 confers on erythroleukemic cells a phenotype of IL-5-dependent growth.

We have established a human IL-5 (hIL-5) dependent cell line, JYTF-1, derived from TF-1 parental human erythroleukemic cells by long-term cultivation in the presence of hIL-5. The ED50 values of hIL-5 for both TF-1 and JYTF-1 cell lines remained similar. However, when cells were grown in an optimal concentration of IL-5, some TF-1 cells but not JYTF-1 cells died via apoptosis. Although the rates of DNA synthesis were similar for TF-1 and JYTF-1 cells grown in IL-5, [3-H]thymidine releasing of pulse-labeled DNA analysis indicated that the viable TF-1 cells in IL-5 were more apoptosis-prone than were JYTF-1 cells. Therefore, in the JYTF-1 variant, the ability to suppress apoptosis has apparently been restored. The following findings suggest that overexpression of the hIL-5 receptor alpha-chain may be responsible for restoring the apoptosis suppression ability of IL-5: 1) the growth of JYTF-1 cells remained cytokine-dependent; 2) the proliferation of JYTF-1 cells in IL-5 was not mediated by autocrine secretion; 3) JYTF-1 and TF-1 cells responded similarly to other cytokines such as human erythropoietin; 4) Northern blot analysis revealed that JYTF-1 cells expressed approximately eightfold more IL-5 receptor alpha-chain mRNA than did TF-1. To our knowledge, JYTF-1 represents the first example in which coupling of mitogenesis stimulation and apoptosis suppression from otherwise uncoupled parental cells confers a phenotype of IL-5-dependent growth.

Apoptosis↗
PubMed1995

Wheat germ agglutinin stabilization of erythrocyte shape: role of bilayer balance and the membrane skeleton.

The effects of wheat germ agglutinin (WGA), Limulus lectin, and concanavalin A on cell shape changes were examined in human erythrocytes. These agents inhibited echinocytosis in cells having elevated cytosolic Ca2+ or incorporated foreign phosphatidylcholine, but had no effect on cell stomatocytosis in response to incorporated phosphatidylserine. The role of the membrane skeleton in this selective membrane fixation was examined. WGA inhibited echinocytosis in cells previously depleted of polyphosphoinositides to reduce membrane skeleton binding to transmembrane proteins, treated with phorbol ester to enhance protein 4.1 phosphorylation, heat-treated to denature spectrin, alkylated with p-chloromercuribenzoate to dissociate glycophorin from the membrane skeleton, or subjected to elevated cell 2,3-diphosphoglycerate to alter organization of the spectrin-actin-protein 4.1 complex. Limulus lectin and increased concentrations of WGA also stabilized discoid shape in pronase-digested cells containing no detectable intact glycophorin. In contrast, cell digestion with sialidase abolished the shape-stabilizing effect of WGA. The results suggest that the membrane skeleton is not involved in WGA shape stabilization. Rather, they suggest that glycoproteins and glycolipids interact with the lectin to stabilize cell surface molecular associations, forming a superficial calyx that inhibits outward, but not inward, membrane bending.

Adult↗
PubMed1995

Clinical experience with the long-term use of 1% apraclonidine. Incidence of allergic reactions.

OBJECTIVE: To identify the incidence and characteristics of allergic reactions associated with the long-term use of 1% apraclonidine hydrochloride. METHODS: We undertook a retrospective analysis of 64 patients receiving long-term 1% apraclonidine therapy at the University of California-San Francisco Glaucoma Service. Patients were excluded if the duration of treatment was less than 2 weeks. Demographic data, initial intraocular pressure response, and incidence and characteristics of allergic reactions were obtained through chart review. Student's t test and chi 2 analysis were used to analyze the demographic data, and Kaplan-Meier survival analysis was used to estimate the long-term incidence of local reactions. RESULTS: Sixty-four patients met the criteria for the study. Of these, 31 (48%) developed an allergic reaction (responders) that led to discontinuation of treatment with the medication, with a mean latency of 4.7 months. Mean follow-up was 13.3 months. Patients free of local reactions (nonresponders) for at least 10 months were able to successfully continue apraclonidine use. Responders tended to be older and female. CONCLUSIONS: Our data are specific for the 1% preparation; however, physicians prescribing apraclonidine on a long-term basis should be aware of possible allergic reactions. A substantial percentage of patients developed this side effect, but most tolerated the medication for up to 4 months, and those without a local reaction after 10 months appeared to be able to continue apraclonidine use indefinitely. This allergic reaction is likely related to the adrenergic agent itself, and not to preservatives.

Adrenergic alpha-Agonists↗
PubMed1995

Differentiation dependent expression of tensin and cortactin in chicken osteoclasts.

The expression and localization of tensin and cortactin were examined in osteoclast precursors in comparison with isolated osteoclasts on various substrates. Initially, the ability of hen monocytes to differentiate into osteoclasts was evaluated on plastic or glass, and compared to differentiation on bone. Specifically, monocytes were isolated from the medullary bones of egg-laying hens maintained on a Ca-deficient diet. Differentiation was monitored morphologically and by quantitation of the ability to form Howship's lacunae in bone slices or resorb radiolabeled bone particles of 20-53 microns diameter. These cells differentiated into tartrate resistant acid phosphatase (TRAP)-positive, bone resorbing, multinucleated syncytia in the presence of cytosine-1-beta-D-arabinofuranoside in a time dependent manner (day 1-6). Differentiation into osteoclast-like cells was similar whether cultured on plastic, on glass, or on bone. When compared to GAP-DH control levels, tensin and cortactin mRNA levels increased by 7- and 10-fold, respectively, by day 6. Tensin and cortactin protein levels also increased by 6- and 15-fold, respectively, by day 6. Immunofluorescence of differentiating precursors showed that tensin localized between regions of cell to cell contact and colocalized with vinculin in podosomes of osteoclast-like cells and of real osteoclasts. Cortactin immunofluorescence was not detectable in monocytes but localized inside tensin/vinculin podosome structures after fusion into osteoclast-like cells and in freshly isolated osteoclasts. Both tensin and cortactin were associated with attachment complexes used by osteoclast-like cells and osteoclasts to resorb bone. Specifically, punctate cortactin staining was observed inside tensin staining which formed a double ring structure at the membrane/bone interface of resorbing osteoclasts. These data showed that tensin and cortactin can be used as osteoclast differentiation markers, that participate in attachment complexes used to resorb bone, and that tensin may participate in the fusion process of osteoclast precursors.

Animals↗