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]     

Cycloalkylpyranones and cycloalkyldihydropyrones as HIV protease inhibitors: exploring the impact of ring size on structure-activity relationships

Previously, 3-substituted cycloalkylpyranones, such as 2d, have proven to be effective inhibitors of HIV protease. In an initial series of 3-(1-phenylpropyl) derivatives with various cycloalkyl ring sizes, the cyclooctyl analog was the most potent. We became interested in exploring the influence of other structural changes, such as substitution on the phenyl ring and saturation of the 5,6-double bond, on the cycloalkyl ring size structure-activity relationship (SAR). Saturation of the 5,6-double bond in the pyrone ring significantly impacts the SAR, altering the optimal ring size from eight to six. Substitution of a sulfonamide at the meta position of the phenyl ring dramatically increases the potency of these inhibitors, but it does not change the optimal ring size in either the cycloalkylpyranone or the cycloalkyldihydropyrone series. This work has led to the identification of compounds with superb binding affinity for the HIV protease (Ki values in the 10-50 pM range). In addition, the cycloalkyldihydropyrones showed excellent antiviral activity in cell culture, with ED50 values as low as 1 microM.     

Utility of catalytic models in the estimation of incidence and prevalence of malaria in a hyperendemic situation

Simple catalytic models were used for estimating the true incidence of malaria in hyperendemic villages of Koraput District in Orissa State where Plasmodium falciparum is predominant. The hill top villages recorded a slide positive rate of 45.68. The daily rate of inoculation among infants was estimated to be 0.00781. The inoculation rate was so high that the recovery from one infection was compensated by the subsequent infection and hence the prevalence continued to increase with age. The model adequately represents the observed data for infants but could not be used for estimating the true prevalence in the adult population without incorporating other factors like immunity and superinfection.     

Long-term intraocular pressure control after cataract extraction with trabeculectomy: phacoemulsification versus extracapsular technique

Mutations of the p53 gene are associated with a number of non-lymphoid cancers of the dog. The present study investigates the p53 gene status within canine patients treated for primary and secondary lymphoma. Three out of eight patients exhibited p53 gene mutations. These included one patient with a germ line mutation and two patients with de novo p53 mutations associated with the secondary lymphoma. Allelic loss of the p53 gene was also observed within primary and secondary tumours of the three canine patients. The results indicate that germ line p53 mutations exist in dogs and may be involved in the known predisposition of some breeds to cancer. The presence of therapy-related p53 point mutations was found to be associated with chemoresistant secondary lymphomas. A causative role for DNA-damaging chemotherapy in de novo mutation of the p53 gene is discussed. Characterization of p53 inactivation in canine tumorigenesis may provide a valuable clinical model for assessing the efficacy and optimal therapeutic regimens of anti-cancer agents.     

Study of in vivo tumor state and response to therapy by analysis of DNA distribution

Comparative studies of cefamandole and cephalothin were carried out in 32 cancer patients. After rapid intravenous injection of 1 gm cefamandole or cephalothin, the peak mean serum concentrations in 11 patients achieved at 0.25 hr were 103.4 mcg/ml and 56.7 mcg/ml, respectively. Except at 6 hr, the serum concentration of cefamandole was higher (p less than 0.05) at all times. The terminal half-lives (t 1/2) were similar, being 1.2 hr for cefamandole and 1.0 hr for cephalothin. Cefamandole, 1 gm intramuscularly, induced a peak mean serum concentration of 26.6 mcg/ml at 1 hr, with a slow decay. Intermittent cefamandole (2 gm intravenously every 6 hr) induced very high mean serum concentrations (7 patients), but at 4 hr the concentrations were similar to those after 1 gm intravenously. Per cent of urinary excretion was similar for both drugs regardless of dose and mode of administration. Continuous-infusion cefamandole or cephalothin (2 gm loading followed by 2 gm every 6 hr) in 14 patients showed consistently higher serum concentrations for cefamandole (p less than 0.05) over a 5-day period. There was no evidence of drug accumulation in the multiple-dose studies. Both the single- and multiple-dose schedules were well tolerated.     

Metabolism of monoterpene alcohol, linalool, by a soil pseudomonad

A microorganism of the genus Pseudomonas has been isolated from the soil by enrichment culture techniques with linalool(I) as the sole source of carbon and energy. The organism is also capable of utilizing limonene, citronellol, and geraniol as substrates but fails to grow on citral, critranellal, and 1,8-cineole. Fermentation of linalool by this bacterium in a mineral salt medium results in the formation of 10-hydroxylinalool(II), oleuropeic acid (IX), 2-vinyl-2-methyl-5-hydroxyisopropyl-tetraphydrofuran)linalool oxide, V), 2-vinyl-2-methyl-tetrahydrofuran-5-one(unsaturated lactone, VI), and few unidentified minor metabolities. Probable pathways for the biodegradation of linalool are presented.