A convergent approach to the synthesis of lipid A

To accomplish the synthesis of compounds having the essential structural features of bacterial lipid A, one must assemble a glucosamine disaccharide bearing five to seven substituents (fatty acyl groups, phosphate ester groups) at specific positions. In the convergent synthesis described, a protected glycoside prepared from D-glucosamine hydrochloride serves as the common intermediate from which both halves of the lipid A structure are fashioned. The glycoside is then converted, by separate series of reactions, into precursors of the reducing half and the nonreducing half of the molecule. The coupling of these precursors yields a product that is readily processed into analogues of lipid A.

Monoclonal antibodies for the rapid diagnosis of respiratory syncytial virus infection by immunofluorescence

Eight separate monoclonal antibodies to the Long strain of respiratory syncytial virus (RSV) were tested for their utility as rapid diagnostic reagents in immunofluorescence. Preliminary screening indicated that all 8 reacted with 11 field strains from three previous local RSV outbreaks and with 4 of 5 additional strains chosen because of their antigenic diversity by neutralization. Two monoclonal antibodies, one each directed against a surface glycoprotein and the nucleocapsid protein, were then compared, singly and combined, with a polyclonal antiserum as diagnostic reagents in 209 consecutive samples submitted to our diagnostic laboratory. Agreement between the two monoclonal antibodies was 100% and between them and the polyclonal serum was 98%. Sensitivity in relation to culture was 96-98%. Monoclonal antibodies are excellent immunofluorescent diagnostic reagents; antigenic diversity among RSV strains was not an impediment to their use in this study.

Role of the cellular oxidation-reduction state in methotrexate binding to dihydrofolate reductase and dissociation induced by reduced folates

5-Formyltetrahydrofolate promotes the net dissociation of methotrexate bound to dihydrofolate reductase in the Ehrlich ascites tumor (L. H. Matherly et al., Cancer Res., 43: 2694-2699, 1983). Treatment of Ehrlich tumor cells with glucose or inhibitors of electron transfer stabilized the association of the antifolate with dihydrofolate reductase as reflected by a 2-fold increased fraction of dihydrofolate reductase-bound methotrexate and an abolition of the 5-formyltetrahydrofolate-induced dissociation of the inhibitor-enzyme complex. Glucose and azide were also found to increase the intracellular ratio of reduced nicotinamide adenine dinucleotide phosphate (NADPH) to oxidized nicotinamide adenine dinucleotide phosphate (NADP+) in the tumor approximately 8- and 11-fold, respectively. However, other agents which enhanced the association between methotrexate and its target enzyme were less effective in increasing the intracellular level of NADPH relative to NADP+. Micromolar concentrations of NADPH promoted methotrexate binding to the purified Ehrlich tumor dihydrofolate reductase. Bound methotrexate could be dissociated from the purified enzyme by 5-methyltetrahydrofolate but less readily by 5-formyltetrahydrofolate and only in the presence of reduced levels of NADPH relative to NADP+. The tetraglutamate derivative of 5-methyltetrahydrofolate was even more effective than the underivatized compound in dissociating methotrexate from dihydrofolate reductase. These findings suggest a critical role for the cellular oxidation-reduction state in determining the affinity of dihydrofolate reductase for methotrexate and thus the cellular sensitivity to the antifolate. In addition, the data are consistent with the possibility that dihydrofolate reductase is a key locus for intracellular competitive interactions between reduced folates and methotrexate during leucovorin rescue from the pharmacological effects of the antifolate.

Glucosamine-derived phospholipids in Escherichia coli. Structure and chemical modification of a triacyl glucosamine 1-phosphate found in a phosphatidylglycerol-deficient mutant

Certain Escherichia coli mutants defective in phosphatidylglycerol biosynthesis accumulate novel glucosamine-derived phospholipids. We previously demonstrated that the simplest of these substance (lipid X) is a diacylglucosamine 1-phosphate bearing beta-hydroxymyristoyl groups at positions 2 and 3 (Takayama, K., Qureshi, N., Mascagni, P., Nashed, M. A., Anderson, L., and Raetz, C. R. H. (1983) J. Biol. Chem. 258, 7379-7385). We now report the structural characterization of a triacylglucosamine 1-phosphate (designated lipid Y) that is also found in these mutants. Hydrolyzates of Y contain 2 mol of beta-hydroxymyristate and 1 mol of palmitate/mol of glucosamine. In the lipid, one of the beta-hydroxymyristates is amide-linked at position 2, while the two other fatty acyl groups are ester-linked. Fast atom bombardment mass spectrometry is used to confirm that Y is a monosaccharide derivative and that the molecular weight of Y as the free acid (C50H96NO13P) is 950.29. Analysis of Y by proton NMR spectroscopy at 200 MHz reveals that the anomeric configuration is alpha. Further, one of the esterified fatty acid residues is attached to the 3 OH of the sugar, while the second is linked to an OH moiety of a hydroxymyristate. The 4 and 6 OH groups of the sugar are unsubstituted, as in E. coli lipid X. To establish the precise location of each esterified fatty acyl residue, we subjected Y to a very mild alkaline hydrolysis in the presence of triethylamine. This resulted in the selective removal of a single hydroxymyristoyl group. The triethylamine-treated derivative (lipid Y) has a molecular weight of 723. NMR spectroscopy of Y shows that the 3 OH of the sugar is no longer substituted, while the beta OH of the remaining amide-linked hydroxymyristate is still esterified with palmitate. On the basis of these findings, we propose that lipid Y has the same fundamental structure as lipid X, except for the additional presence of a palmitoyl moiety on the N-linked hydroxymyristate. Presumably, lipid Y is synthesized from X by a selective acylation reaction.

Krimpsiekte and acute cardiac glycoside poisoning in sheep caused by bufadienolides from the plant Kalanchoe lanceolata Forsk

Three toxic bufadienolides , one characterized as hellibrigenin 3-acetate, have been isolated from Kalanchoe lanceolata Forsk. Typical signs of cardiac glycoside poisoning, involving the gastro-intestinal, neuromuscular and cardiovascular systems, could be induced by drenching the milled plant to sheep. Such signs could also be induced by dosing the bufadienolides to sheep or by injecting them into both guinea-pigs (subcutaneously) and sheep (intravenously). The specific paretic syndrome, krimpsiekte , on the other hand, was reproduced only by the repeated intravenous administration of smaller doses of the 2 unknown bufadienolides to sheep. Histopathological examination revealed a mild to severe multifocal cardiomyopathy in sheep receiving plant material or bufadienolides .

The experimental production of krimpsiekte in sheep with Tylecodon grandiflorus (Burm.f.) Toelken and some of its bufadienolides

Six bufadienolides were isolated from Tylecodon grandiflorus ( Burm .f.) Toelken . The paretic syndrome, krimpsiekte , could be induced in sheep either by repeated oral administration of small quantities of plant material or the intravenous injection of small quantities of certain bufadienolides . A mild to moderate, acute to subacute, multifocal cardiomyopathy was evident in sheep poisoned by both the plant and the bufadienolides .

Intravesical chemotherapy in urinary bladder cancer

Monthly instillation therapy with Adriamycin in a standardized dose of 300 ng/ml/h together with a phosphate buffer at pH 7.4 seems to give satisfactory results in patients with primary bladder carcinoma in situ and in patients with secondary carcinoma in situ of the bladder who have previously received full courses of irradiation. The side-effects are transient and few.

Inhibition of Na+-Ca2+ exchange in rat brain by amiloride

Amiloride (N-amidino-3,5-diamino-6-chloropyrazine carboxamide) reversibly inhibits Na+-dependent 45Ca2+ uptake (Na+-Ca2+ exchange) by plasmalemma-enriched vesicles prepared from microsomes of rat cerebral cortex and by vesicles from osmotically shocked synaptosomes. The drug inhibits Na+-dependent Ca2+ uptake in a competitive manner with a KI of 0.25-0.34 mM. Na+-dependent 45Ca2+ efflux from vesicles is also inhibited by extravesicular amiloride. The drug does not appear to affect nonmitochondrial ATP-dependent Ca2+ transport in these vesicle preparations. Membranes containing Na+-Ca2+ carrier can be solubilized in Na+-cholate and reconstituted into phospholipid vesicles. Na+-dependent Ca2+ uptake by the vesicles is inhibited by amiloride.

[Adriamycin instillations in carcinoma in situ of the bladder]

Several authors have described the regressive effect of the instillation of adriamycin on the cell appearance of carcinoma in situ. This applies to both weekly and monthly administration. The problem lies in the interpretation of the cytologic picture after instillation. DNA analysis could possibly improve the diagnostic reliability.

Fatty acyl derivatives of glucosamine 1-phosphate in Escherichia coli and their relation to lipid A. Complete structure of A diacyl GlcN-1-P found in a phosphatidylglycerol-deficient mutant

We have determined the complete structure of a glycolipid (designated lipid X) previously found to accumulate in certain Escherichia coli mutants defective in phosphatidylglycerol synthesis (Nishijima, M., and Raetz, C.R.H. (1979) J. Biol. Chem. 254, 7837-7844). Based on fast atom bombardment mass spectrometry and proton nuclear magnetic resonance studies, this substance is an acylated metabolite of glucosamine 1-phosphate. Lipid X of E. coli has a Mr = 711.87 as the free acid (C34H66NO12P) and contains two beta-hydroxymyristate moieties, one attached as an amide at the 2 position and the other as an ester at the 3 position of the sugar. It has free hydroxyl groups at the 4 and 6 positions, and the anomeric configuration is alpha. The structure of lipid X from E. coli closely resembles the reducing end subunit of lipid A, and it might represent a very early precursor in the biosynthesis of lipid A. To our knowledge, fatty acyl derivatives of glucosamine 1-phosphate have not been reported previously.

Production of cytotoxic canthin-6-one alkaloids by Ailanthus altissima plant cell cultures

Ailanthus altissima (Mill.) Swingle was established as callus- and cell-suspension cultures. Canthin-6-one and 1-methoxycanthin-6-one were isolated by a combination of preparative tlc and preparative hplc. The two alkaloids were identified by their uv, ms, and 1H-nmr spectra. The combined yield of the two alkaloids was 1.38% of dry weight from callus and 1.27% of dry weight from cell suspensions. The cytotoxicities of canthin-6-one, 1-methoxycanthin-6-one, 5-methoxycanthin-6-one, and canthin-6-one-3-N-oxide to guinea pig ear keratinocytes have been compared, and the IC50 values range from 1.11 to 5.76 micrograms/ml. There is no significant difference in activity among these four cytotoxic alkaloids.

Permanent Iodine-125 implants in head and neck cancer

One hundred twenty-four patients were treated with advanced recurrent head and neck cancer for palliation with radioactive permanent Iodine-125 (125I) implants. Complete regression occurred in 71% of the 118 lesions for which evaluation was possible and greater than 50% regression occurred in 18%; no meaningful regression occurred in 11%. Local recurrence of cancer was subsequently seen in 21% of the lesions which had regressed completely, in 55% of those which had regressed incompletely, and in 100% of those which had not regressed. The incidence of serious complications was 5.5%. Overall, in 64% of the instances the implanted lesions remained controlled until the patient's death, usually due to progression of cancer elsewhere in the body. It is concluded that permanent 125I implants offer useful palliation to the patient with recurrent head and neck cancer with a minimum of toxicity and inconvenience. Because of their low toxicity even after prior full-course external radiation therapy, the authors are currently investigating their use as planned adjunct to external radiation therapy and chemotherapy in the initial definitive management of patients with locally advanced head and neck cancer.

Oligosaccharides from "standardized intermediates". The 2-amino-2-deoxy-D-galactose analog of the blood-group O(H) determinant, type 2, and its precursors

The selectively benzylated glycoside allyl 2-acetamido-4,6-di-O-benzyl-2-deoxy-beta-D-galactopranoside (4) was prepared from the corresponding derivative of 2-acetamido-2-deoxy-D-glucose via the p-bromobenzenesulfonate and the benzoate. 2-O-Benzoyl-3,4,6-tri-O-benzyl-alpha-D-galactopyranosyl (10) was obtained from allyl 6-O-benzyl-2-O-(2-butenyl)-alpha-D-galactopyranoside via known intermediates. To complete the sequence, the 1-propenyl 3,4,6-tri-O-benzyl galactoside was successively converted into the 2-benzoate, the free sugar, and the chloride 10. A fully protected form (11) of the trisaccharide alpha-L-Fucp-(1 leads to 2)-beta-D-Galp-(1 leads to 4)-D-GalNAc was then synthesized by coupling 10 to 4, partially deblocking the disaccharide product, and L-fucosylating the resulting intermediate. Cleavage of the O-benzyl groups from 11, with concomitant saturation of the allyl group, gave the propyl beta-glycoside of the unsubstituted trisaccharide.

Oligosaccharides from "standardized intermediates". Synthesis of a branched tetrasaccharide glycoside isomeric with the blood-group B, type 2 determinant

Building block derivatives of the component monosaccharides were used to construct the tetrasaccharide glycoside 15, in which an alpha-D-Galp-(1 leads to 4)-D-Gal linkage replaces the alpha-(1 leads to 3) linkage of the human blood-group B, type 2, determinant structure. The initial coupling of 2-O-benzoyl-3,6-di-O-benzyl-4-O-(tetrahydropyran-2-yl)-alpha-D-galactopyranosyl chloride to allyl 2-acetamido-3,6-di-O-benzyl-2-deoxy-beta-D-glucopyranoside was followed by selective deprotection of the disaccharide product, either at O-4' (to give 8) or O-2' (to give 3). The conversion of 8 into 15 involved successive coupling with tetra-O-benzyl-alpha-D-galactopyranosyl bromide (8 leads to 11), O-debenzoylation at O-2' (11 leads to 12), coupling with tri-O-benzyl-alpha-L-fucopyranosyl bromide (12 leads to 14), and O-debenzylation by hydrogenolysis (14 leads to 15). Alternatively, 3 was alpha-L-fucosylated to give 6, and 6 was selectively deprotected at O-4' to give 7. However, attempts to alpha-D-galactosylate 7 were unsuccessful. The unsubstituted forms of the intermediate disaccharide (8) and trisaccharide (12) glycosides were obtained by appropriate deblocking procedures.

Diarrhea in breast-fed and non-breast-fed infants

During the first year of life a group of babies was prospectively observed for diarrhea and for fecal carriage of heat-labile toxigenic bacteria, with or without colonization factor, and rotavirus. Approximately half of the babies were breast-fed for the first six months of life. There was no difference between groups (breast-fed vs non-breast-fed) in number of babies who had diarrhea during any two-month period. Nor was there any difference between groups in the number of babies who had diarrhea while carrying toxigenic bacteria, with or without colonization factor. Secretory antibody to toxin was found in 37% of colostrum and milk samples. There was a small but insignificant difference in the number of babies who had diarrhea when they carried toxigenic bacteria depending on the presence of antibody in the breast milk they received.

Alkaloid production by leaf organ, root organ and cell suspension cultures of Cinchona ledgeriana

The alkaloids produced by leaf organ, root organ and root suspensions of two varieties of Cinchona ledgeriana have been determined quantitatively by HPLC. In contrast to previous findings, the root organs and root suspensions yielded quinine and quinidine. The root cells release alkaloids into the suspension medium.