Evidence that neomycin inhibits binding of herpes simplex virus type 1 to the cellular receptor.

The effect of neomycin, a phosphoinositide-binding aminoglycoside, on herpes simplex virus type 1 (HSV-1) infection of BHK cells was studied. We showed earlier that it specifically inhibits HSV-1 production but not HSV-2 production (Langeland et al., Biochem Biophys. Res. Commun. 141:198-203, 1986). We now show that neomycin had no effect on cellular protein synthesis, as judged by the appearance of 35S-labeled polypeptides separated by polyacrylamide gel electrophoresis. Virus-induced polypeptides, however, were strongly inhibited at neomycin concentrations above 2 mM. Comparison among different aminoglycosides showed a variation in inhibition of HSV-1 production that paralleled the cationic charge of the aminoglycosides. HSV-1 receptor binding at 4 degrees C was completely inhibited by neomycin. At 37 degrees C both receptor binding and internalization, as measured by an indirect assay, appeared to be inhibited by more than 90%. The effect of neomycin on the infection was almost immediate upon the addition of the drug and preceded virus internalization. Possible mechanisms of the neomycin effect are discussed.     

Herpes simplex virus-1-specific proteins are involved in alteration of polyphosphoinositide metabolism in baby-hamster kidney cells.

Herpes simplex virus type 1 (HSV-1) induces altered phosphoinositide metabolism in baby hamster kidney (BHK) cells, measured as incorporation of [3H]inositol or [32P]Pi [Langeland, Haarr & Holmsen (1986) Biochem. J. 237, 707-712]. We now report that this response in the inositol phospholipids is dependent on virus-specific proteins synthesized in the beta (early) stage of virus protein synthesis. This was demonstrated both by resistance to the inhibitory effect of cycloheximide after this stage of infection, and by the use of temperature-sensitive (ts) mutants of HSV-1; ts mutants in which protein synthesis was blocked so that only the alpha proteins were expressed showed a PIP2/PIP (phosphatidylinositol 4,5-bisphosphate/phosphatidylinositol 4-monophosphate) ratio similar to uninfected cells, while ts mutants which were defective in protein synthesis at a late beta stage or later showed increased PIP2/PIP ratios similar to cells infected by wild type HSV-1.     

Evidence that neomycin inhibits HSV 1 infection of BHK cells

The effect of neomycin on the Herpes Simplex Virus (HSV) type 1 and 2 infection of baby hamster kidney cells was studied. Neomycin concentrations of 3 mM or more caused a more than 90% inhibition of HSV 1 proliferation, while it had no effect on HSV 2 proliferation, measured as plaque-forming units. Furthermore, neomycin must be present at the time of infection in order to exert full effect, addition 1 hour postinfection was comparable to untreated cells. This indicates that neomycin may specifically interfere with very early stages of HSV 1 infection.     

Different responses to changes in phosphorus,P, among lakes. A study of slopes in chl-a = f(P) graphs

The least squares estimator of a linear regression coefficient _L will give an overall expression for the change in with x. In fresh water ecology, however, subgroups, % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamiuaSGaci% 4Aaaaa!37BE!\[P\operatorname{k}\], of a parent population may have slopes which differ from the overall slope, _L. By constructing frequency histograms for the set of angles: Arctang % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaci4uaSGaam% yAaiaadQgaaaa!38AE!\[\operatorname{S} ij\],% MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaci4uaSGaam% yAaiaadQgaaaa!38AE!\[\operatorname{S} ij\]= para sa y and x% MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaaiikaiaadM% faliaadMgakiabgkHiTiaadMfaliaadQgakiaacMcacaGGVaGaaiik% aiaadIhaliaadMgakiabgkHiTiaadIhaliaadQgakiaacMcaaaa!42F0!\[(Yi - Yj)/(xi - xj)\], i < j, % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamiEaSGaam% yAaOGaeyiyIKRaamiEaSGaamOAaaaa!3BAB!\[xi \ne xj\], peaks in the distribution may be identified and related to ecological phenomenon. To identify peaks we fit Gaussian distributions to the frequency histograms. For a set consisting of 142 observations of chlorophyll-a and total phosphorus (nutrient) concentrations (TP) from 16 lakes we found four Gaussian peaks corresponding to four subgroups, % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamiuaSGaci% 4Aaaaa!37BE!\[P\operatorname{k}\]k = 1,4. One group identified a response of chl-a to changes in TP which correspond approximately to the average slope found by least square regression (the slope was 0.49). The second group consisted of steeper response than the average (1.28). A third group showed that there is an enhanced proportion of cases where chl-a does not respond to TP (zero slope, all the three deep lakes > 10 m, included in the date set contributed to this group). The size of the last group, spanning a wide range of slopes, suggested that about 30% of the inter annual changes in chl-a is unrelated to TP. The results are compared to result obtained by simple least squares regression and to the Theil non-parametric slope estimator.     

Activated platelet-derived growth factor autocrine pathway drives the transformed phenotype of a human glioblastoma cell line

Human glioblastoma cells (A172) were found to concomitantly express PDGF-BB and PDGF β-receptors. The receptors were constitutively autophosphorylated in the absence of exogenous ligand, suggesting the presence of an autocrine PDGF pathway. Neutralizing PDGF antibodies as well as suramin inhibited the autonomous PDGF receptor tyrosine kinase activity and resulted in up-regulation of receptor protein. The interruption of the autocrine loop by the PDGF antibodies reversed the transformed phenotype of the glioblastoma cell, as determined by (1) diminished DNA synthesis, (2) inhibition of tumor colony growth, and (3) reversion of the transformed morphology of the tumor cells. The PDGF antibodies showed no effect on the DNA synthesis of another glioblastoma cells line (U343MGa 31L) or on Ki-ras-transformed fibroblasts. The present study demonstrates an endogenously activated PDGF pathway in a spontaneous human glioblastoma cell line. Furthermore, we provide evidence that the autocrine PDGF pathway drives the transtormed phenotype of the tumor cells, a process that can be blocked by extracellular antagonists. © 1994 Wiley-Liss, Inc.     

Drug induced changes in cardio-vascular parameters in the Atlantic cod,Gadus morhua

Summary Ventral (VAP) and dorsal (DAP) aortic blood pressure, heart rate (HR) and cardiac output ( ) were recorded simultaneously in unanaesthetized Atlantic cod, and the effects of vasoactive drugs on the cardio-vascular parameters studied. Mean resting values for the parameters were VAP=4,39 kPa, DAP=2,49 kPa, HR=41 beats/min, and = 29,1 ml/min×kg. Adrenaline constricted the systemic vasculature, dilated the branchial vasculature and caused a decrease of HR and due to a cholinergic reflex. After atropine pre-treatment this reflex was abolished, and the effect of adrenaline on blood pressure enhanced. A small decrease in persisted after atropine, presumably reflecting the effect of an increased end-systolic afterload.Phenylephrine produced a weak increase in systemic vascular resistance, while isoprenaline lowered both systemic and branchial vascular resistance. The effect of isoprenaline is probably mediated by beta adrenoceptors in both vascular beds, since propranolol antagonizes the effect.Acetylcholine in low doses produces a drop in without affecting HR, while higher doses also stop the heart. There is no significant change in either branchial and systemic vascular resistance after acetylcholine.Abbreviations VAP mean ventral aortic blood pressure - DAP mean dorsal aortic blood pressure - TBPD trans-branchial blood pressure drop - HR heart rate - SV stroke volume - cardiac output (ventral aortic blood flow) - VR _g branchial vascular resistance - VR _s systemic vascular resistance     

Metal-directed affinity labeling of zinc(II), cobalt(II) and cadmium(II) horse liver alcohol dehydrogenases

The active site metal in horse liver alcohol dehydrogenase has been studied by metal-directed affinity labeling of the native zinc(II) enzyme and that substituted with cobalt(II) or cadmium(II). Reversible binding of bromoimidazolyl propionic acid to the cobalt enzyme blueshifts the visible absorption band originating from the catalytic cobalt atom at 655 to 630 nm. Binding of imidazole to the cobalt(II) enzyme redshifts the 655 nm band to 667 nm. Addition of bromoimidazolyl propionic acid blueshifts this 667 nm band back to 630 nm. This proves direct binding of the label to the active site metal in competition with imidazole. The affinity of the label for the reversible binding site in the three enzymes follows the order Zn ? Cd ? Co. After reversible complex formation, bromoimidazolyl propionic acid alkylates cysteine-46, one of the protein ligands to the active site metal. The nucleophilic reactivity of this metal-mercaptide bond in each reversible complex follows the order Co ? Zn ? Cd.