LEC18, a dominant Chinese hamster ovary glycosylation mutant synthesizes N-linked carbohydrates with a novel core structure

The dominant Chinese hamster ovary cell glycosylation mutant, LEC18, was selected for resistance to pea lectin (Pisum sativum agglutinin (PSA)). Lectin binding studies show that LEC18 cells express altered cell surface carbohydrates with markedly reduced binding to 125I-PSA and increased binding to 125I-labeled Datura stramonium agglutinin (DSA) compared with parental cells. Desialylated [3H]Glc-labeled LEC18 cellular glycopeptides that did not bind to concanavalin A-Sepharose exhibited an increased proportion of species that were bound to DSA-agarose. Most of these glycopeptides bound to ricin-agarose and were unique to LEC18 cells. This fraction was purified from approximately 10(10) cells and shown by 1H NMR spectroscopy and methylation linkage analysis to contain novel N-linked structures. Digestion of these glycopeptides with mixtures of beta-D-galactosidases and N-acetyl-beta-D-glucosaminidases gave core glycopeptides that, in contrast to cores from parental cells, were mainly not bound to concanavalin A-Sepharose or to PSA-agarose. 1H NMR spectroscopy, matrix-assisted laser desorption ionization/time of flight mass spectrometry, electrospray mass spectrometry, and collision-activated dissociation mass spectrometry showed that the LEC18 core glycopeptides contained a new GlcNAc residue that substitutes the core GlcNAc residues. Methylation linkage analysis of the parent compound provided evidence that the GlcNAc is linked at O-6 to give the following novel, N-linked core structure. [formula: see text]     

Native and oxidized low density lipoproteins modulate mesangial cell apoptosis

Hyperlipidemia has been demonstrated to contribute to hypercellularity of the mesangium in experimental animal models of glomerulosclerosis. We studied whether it also has the potential to convert a hypercellular mesangium into a hypocellular one by inducing mesangial cell (MC) apoptosis. Low density lipoprotein (LDL) enhanced (P < 0.001) mouse mesangial cell (MMC) proliferation at lower concentrations (control, 10.3 +/- 0.3 vs. LDL 100 micrograms/ml, 24.2 +/- 0.3 x 10(4) cells/ml) but augmented (P < 0.001) apoptosis at higher concentrations (control, 5.6 +/- 0.5% vs. LDL, 500 micrograms/ml 26.2 +/- 3.4% apoptotic cells/field). Oxidized (OX) LDL enhanced MMC apoptosis in concentrations of 50 to 200 micrograms/dl. There was a direct relationship between MMC apoptosis and oxidation of LDL as judged by measuring thiobarbituric acid reactive species (TBARS). Since superoxide dismutase (SOD) attenuated (P < 0.001) LDL-induced MMC apoptosis, it seems to be mediated through the generation of free radicals by mesangial cells (control, 4.3 +/- 1.5%; LDL, 200 micrograms/ml, 19.4 +/- 0.5%; LDL + SOD, 8.1 +/- 1.3% apoptotic cells/field). LDL also induced a similar effect on human mesangial cells. These studies were further confirmed by DNA fragment assays and ELISA for programmed cell death. LDL treated cells also showed enhanced mRNA expression for RSG-2, a marker for active cell death. These in vitro results provide a basis for the speculation that LDL has the potential to cause an initial hypercellular and subsequent hypocellular mesangium in the course of the development of glomerulosclerosis.     

Evaluation of anti-nociceptive effects of neuronal nicotinic acetylcholine receptor (NAChR) ligands in the rat tail-flick assay

In the present investigation, anti-nociceptive effects of neuronal nicotinic acetylcholine receptor (NAChR) ligands, (+)- and (-)-nicotine, cytisine, methylcarbamylcholine (MCC), dimethylphenylpiperazinium iodide (DMPP), and (+/-)-epibatidine were evaluated in the rat tail-flick assay both after subcutaneous (s.c.) and intracerebroventricular (i.c.v.) administration. The pharmacology of the tail-flick response to NAChR ligands after s.c. and i.c.v. routes was similar. Epibatidine was the most potent ligand examined with a longer duration of action than any other agonist. (-)-Nicotine was more active than (+)-nicotine indicating stereospecificity. ICV administration studies indicated an apparent partial agonist activity for (+)-nicotine in the tail-flick response. Tail-flick responses to NAChR agonists are independent of opioid and muscarinic pathways and appear to be mediated both by central and peripheral NAChR recognition sites. Central administration of MCC activates both NAChR and muscarinic anti-nociceptive mechanisms. Studies employing the alpha-adrenergic receptor alkylating agent, phenoxybenzamine or the noradrenergic neurotoxin, N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP-4), suggested that the NAChR-noradrenergic and NAChR-serotoninergic interactions play an important role in the tail-flick response. Studies employing a selective alpha-bungarotoxin-sensitive NAChR receptor antagonist, methyllycaconitine (MLA), suggested a minimal role for these receptors in the tail-flick response. The biochemical studies also indicated that a sub-population of NAChR receptors are located pre-synaptically on noradrenergic and/or serotoninergic pathways in the hippocampus.     

Protein accumulation in cerebrospinal fluid during -90 degrees head-down tilt in rabbit

Plasma proteins are only somewhat larger than the intercellular spaces of the cerebral microvessels that constitute the blood-brain barrier or of the choroid plexus villi that elaborate cerebrospinal fluid (CSF). We hypothesized that the integrity of these barriers in anesthetized rabbits might be compromised during head-down tilt (HDT). Plasma protein and osmolality, hematocrit, and CSF protein concentration were compared in rabbits exposed to 1 h of HDT (n = 20) and prone rabbits (n = 10). In addition, the concentration of trypan blue dye, injected intravenously at the end of HDT or the prone position, was measured in brain homogenate. Finally, arterial blood pressure was measured via a catheterized carotid artery. HDT disrupted the barrier between blood and CSF, as indicated by a significantly (P < 0.01) greater brain trypan blue concentration in the HDT rabbits [172.2 +/- 14.4 (SD) micrograms/g dry wt] than in the prone rabbits (29.8 +/- 4.4 micrograms/g dry wt). Moreover CSF protein 5 min after HDT onset was significantly increased compared with control in HDT rabbits (54.6 +/- 1.9 vs. 81.4 +/- 5.2 mg/dl; n = 8) but not in prone rabbits (55.6 +/- 2.7 vs. 57.2 +/- 5.0 mg/dl; n = 6). Changes in the plasma protein-to-hematocrit ratio in the HDT animals, but not in the prone animals, were also compatible with a loss of fluid from the vascular compartment.(ABSTRACT TRUNCATED AT 250 WORDS)     

Presence of genomes of phage PBV-1 in the mycelia of the fungus Penicillium brevi-compactum

Progressive systemic sclerosis may be associated with focal myocardial fibrosis. Electrocardiographic abnormalities including conduction block are common in progressive systemic sclerosis but whether they are due to direct destruction of the specialized conduction tissue of the heart is uncertain. The conduction systems of 35 patients with progressive systemic sclerosis were studied. Of these 35 patients, 17 (50 per cent) had myocardial fibrosis of the type seen in progressive systemic sclerosis. In 10 of the 17, it was severe. Sinus node fibrosis was present in 13 patients and was nearly as frequent in those with as in those without the progressive systemic sclerosis myocardial lesion. Overlying pericarditis may have contributed to the fibrotic changes within the sinoatrial nodes in seven of the 13 patients. The atrioventricular node and main His bundles were normal. However, fibrotic changes were found in the proximal bundle systems in six patients. In three of the six, severe myocardial progressive systemic sclerosis was present, two had focal fibrous atrophy of the left bundle, and one had complete interruption of the right bundle. In only the latter patient was this reflected in the electrocardiogram which showed a right bundle branch block. Three patients without progressive systemic sclerosis myocardial lesions also had fibrous atrophy of a portion of the proximal left bundle branch, and in one the electrocardiogram showed an isolated left anterior hemiblock. Thus, morphologic abnormalities within the conduction system in our patients are difficult to attribute to progressive systemic sclerosis per se. Furthermore, although conduction abnormalities were more frequent in patients with myocardial disease, specific conduction system disease was not the cause in most patients. As has been noted in ischemic heart disease, the conduction system appears to be relatively spared from the myocardial changes of progressive systemic sclerosis, and the high incidence of conduction disturbances in this condition may be a consequence, rather, of damage to working myocardium.     

Topical corticosteroid therapy complicating congenital glaucoma

A 4-month-old infant with congenital glaucoma had been treated with a topical antibiotic-corticosteroid for three months. This fact complicated initial management, delaying definitive diagnosis and therapy. Topical steroid therapy in infants can produce a condition simulating congenital glaucoma. Since there is little rationale for using topical steroids to treat most infantile external disease processes, they are best avoided. When steroids are used for a prolonged period, some strategy for detecting glaucoma should be adopted.     

Potentialities of present day computed tomography in diagnosis of stomach cancer

Based on the findings of 206 examinations, the authors advance their opinion of the role of X-ray computed tomography (XRCT) in the diagnosis of gastric cancer. The authors think that if their developed procedure for X-ray computed tomography based on the use of usual air as the only contrast agent by measuring it out in doses and administering into the gastric at CT scanning, which is called pneumoroentgenocomputered tomography (PRCT), is employed, it, preserving all the traditional, already known, advances of XRCT additionally yields highly valuable information on a direct damage to the gastric wall itself. The findings suggest that PRCT is especially effective in intramurally growing gastric cancers, the so-called squamous carcinomas, which are hardly differentiated for diagnosis and which are most common. Noteworthy is the fact that in seemingly unquestionable exophytic gastric cancer, detecting intramural tumorous infiltration adjacent to the exophyte, PRCT thus provides evidence that the exophyte revealed is the peculiar top of an iceberg, whose base shows a significant exophytic gastric carcinoma.     

Potential adverse outcomes of psychotropic and narcotic drug use in Canadian seniors

Infants who ingest high amounts of fluoride can be at risk of dental fluorosis. The authors analyzed the fluoride concentration of 238 commercially available infant foods. Fluoride concentrations ranged from 0.01 to 8.38 micrograms of fluoride per gram, with the highest fluoride concentrations found in infant foods containing chicken. Infant foods, especially those containing chicken, should be considered when determining total fluoride intake.