Temporal and molecular characteristics of lacZ mutations in somatic tissues of transgenic mice

In order to help establish criteria for optimizing protocols for in vivo mutation studies, lacZ transgenic mice (Muta mouse) were treated with five consecutive daily doses of ethylnitrosourea (50 mg/kg), sampled at times up to 55 days after treatment, and mutant frequencies and DNA sequences determined for liver and bone marrow. In the bone marrow, the mutant frequency rose very rapidly in the first 5 days after treatment to 34 times the control frequency. Subsequently, there was a brood peak where the mutant frequency did not vary significantly, although it did appear to begin to decline after 45 days. In contrast, in the liver, the peak mutant frequency (11 times the control frequency) was not achieved until 35 days, after which there appeared to be a slow decline up to 55 days, which was not statistically significant. Once the maximum mutant frequency was reached, the mutation spectra in the two tissues were indistinguishable. In contrast to the G:C-->A:T transitions in 5'-CpG sites characteristic of untreated mice, A:T-->T:A transversions and A:T-->G:C transitions were prominent in both liver and bone marrow of ENU-treated mice, suggesting the involvement of unrepaired O2- and O4-ethylthymine adducts. In addition, G:C-->T:A transversions were induced in liver. This study demonstrates the possibility that although tissues may have different mutation fixation times, a single mutation fixation time equal to the longest time may be appropriate for in vivo mutation studies, provided that the mutation frequency does not decline appreciably after the peak is reached. This study also illustrates the necessity of ensuring that mutation characteristics are determined after optimal fixation has occurred.     

The novel cuticular collagen Ovcol-1 of Onchocerca volvulus is preferentially recognized by immunoglobulin G3 from putatively immune individuals

The concentration and affinity to concanavalin A (ConA) of plasma alpha 1-acid glycoprotein (AGP) and AGP levels in extracts of liver tissues were investigated in specific-pathogen-free chickens infected with the highly virulent HPS-2 strain or virulent reference GBF-1 strain of infectious bursal disease virus. The plasma AGP value in uninfected control 3- to 7-wk-old chickens was 161.8 +/- 25.8 micrograms/ml (mean +/- SD), and ConA-unreactive and ConA-reactive AGP comprised 47% and 63% of total AGP. Increases in AGP levels in plasma and liver extracts were observed in both the HPS-2 and the GBF-1 groups, although albumin levels decreased. The plasma AGP values were higher in the HPS-2 group than in the GBF-1 group through the experimental period. In the HPS-2 group, ConA-reactive AGP reached levels 6.8-fold greater than control values and comprised 80% of total AGP at 4 days post-inoculation. In the lipopolysaccharide group, a great increase in ConA-reactive AGP was observed.     

Numerical Modeling of Pulsed Raman Fiber Converters at 2 $mu{hbox {m}}$

Theoretical modeling of stimulated Raman scattering (SRS) in fibers is presented for the near-infrared band around 2 mum, where pump and Stokes wave have different absorption. This model takes into account amplified spontaneous emission (ASE), SRS towards Stokes and anti-Stokes waves, absorption of the Raman medium and Rayleigh backscattering in fibers. Depending on the fiber configuration, this model includes the cavity parameters of either external or internal mirrors at the fiber ends. Input parameters are, among others, temporal profiles of the pump radiation, absorption, and gain curve of the Raman medium. The model agrees well with experimental results obtained with a GeO₂ doped core fiber pumped by a pulsed and tunable Tm:silica fiber laser emitting around 2 mum.     

Heterotrimeric G proteins physically associated with the lipopolysaccharide receptor CD14 modulate both in vivo and in vitro responses to lipopolysaccharide

Septic shock induced by lipopolysaccharide (LPS) triggering of cytokine production from monocytes/macrophages is a major cause of morbidity and mortality. The major monocyte/macrophage LPS receptor is the glycosylphosphatidylinositol (GPI)-anchored glycoprotein CD14. Here we demonstrate that CD14 coimmunoprecipitates with Gi/Go heterotrimeric G proteins. Furthermore, we demonstrate that heterotrimeric G proteins specifically regulate CD14-mediated, LPS-induced mitogen-activated protein kinase (MAPK) activation and cytokine production in normal human monocytes and cultured cells. We report here that a G protein binding peptide protects rats from LPS-induced mortality, suggesting a functional linkage between a GPI-anchored receptor and the intracellular signaling molecules with which it is physically associated.     

Immunocytochemical localization of chymase to cytoplasmic vesicles after rat peritoneal mast cell stimulation by compound 48/80

The subcellular events responsible for release of mediators by mast cells may help to clarify roles for mast cells in health and disease. In this study we show that the granule-associated protease chymase is also within cytoplasmic vesicles in appropriately stimulated rat peritoneal mast cells. Rat peritoneal mast cells were recovered before or 1-10 sec after exposure to the secretogogue compound 48/80 (10 micrograms/ml) and then were examined by radioimmunoassay to quantify histamine release or were processed, using routine methods for postembedding immunoelectron microscopy, to identify the subcellular localization of chymase. In comparison to unstimulated cells, compound 48/80 stimulated cells in two independent experiments showed an increase (15%, 28%) in the surface area of the cell and a decrease (12%, 6%) in the surface area of the total granule compartment before degranulation channel formation. These global cellular changes occurred in a background of transient but significant (p < 0.01) increases in the area and number of chymase-immunoreactive vesicles per microns2 cytoplasm. These changes were detectable at 5 or 7 sec after stimulation with compound 48/80 but returned to near prestimulation levels by 9 or 10 sec after addition of compound 48/80 (total cumulative histamine release was 28% by 8 sec and 47% by 14 sec). These observations suggest that vesicles participate in the early stages of regulated secretion of chymase from rat peritoneal mast cells.     

Metabolic mapping of the rat brain after subanesthetic doses of ketamine: potential relevance to schizophrenia

Several lines of evidence suggest the molecular and functional entity of muscarinic M1 receptors in mammalian heart. We have reported that acetylcholine (ACh) reduces the maximum upstroke velocity of action potential (Vmax) through activation of muscarinic M1 receptors, which is followed by a muscarinic M2 receptor-mediated increase. The present study sought to determine whether activation of beta-adrenergic receptors modulates the muscarinic M1 and M2 receptor-mediated effects on Vmax in isolated mouse right atria. Intracellular recordings of spontaneous action potential were done using the conventional glass microelectrode technique. Isoproterenol (3 nM) completely antagonized ACh (5 microM)-induced reduction in Vmax. The antagonism was accompanied by a subsequent increase in Vmax. Propranolol (0.3 microM) abolished the effects of isoproterenol on ACh-induced changes in Vmax. Isoproterenol antagonized McN-A-343 (4-(m-chlorophenyl-carbamoyloxy)-2-butynyltrimethylammonium chloride) (300 microM, a muscarinic M1 receptor agonist)-induced reduction in Vmax. Oxotremorine (0.03 microM), a muscarinic M2 receptor agonist, did not affect Vmax by itself, but significantly increased it in the presence of 3 nM isoproterenol. The effects of isoproterenol were mimicked by cholera toxin (100 nM, 1 hr), a Gs-protein activator, and forskolin (10 nM), a direct activator of adenylyl cyclase. H-89 (N-[2-(p-bromocinnamylamino)ethyl]-5-isoquinolinesulphonamide++ +, 1 microM), a selective protein kinase (PK)-A inhibitor, abolished the antagonism by isoproterenol of ACh-induced reduction in Vmax. The present results suggest that activation of the beta-adrenergic-Gs-adenylyl cyclase system antagonizes ACh-induced reduction (muscarinic M1-mediated) and potentiates the subsequent increase (muscarinic M2 receptor-mediated) in Vmax. The beta-adrenergic antagonism of ACh-induced reduction in Vmax may involve cross-talk between PK-A and PK-C signaling pathways.     

Assessment of atrial septal defect morphology by transthoracic three dimensional echocardiography using standard grey scale and Doppler myocardial imaging techniques: comparison with magnetic resonance imaging and intraoperative findings

The properties of chemically cured and light-cured composite resins were recorded at baseline and at intervals over seven years, while the materials were exposed to controlled storage conditions as well as to various conditions typical of clinical situations. For chemically cured resins in clinical conditions, mechanical properties decreased, and working and setting times increased over four years; if refrigerated (controlled), properties remained constant past seven years. For light-cured resins, test results were constant over the entire seven-year test period regardless of storage conditions. An accelerated aging protocol was developed to allow for the evaluation of the relative storage stability of new and similar materials.