Copolymers of substituted styrenes with vinylidene cyanide or methylvinylidene cyanide. 13C NMR studies of their microstructures

Various copolymers of vinylidene cyanide ( 1a ) and methylvinylidene cyanide ( 1b ) with substituted styrenes ( 2a–g ) were synthesized by radical copolymerization, and their microstructures were studied by ¹³C NMR spectroscopy. The copolymers of vinylidene cyanide with substituted styrenes have a perfectly alternating structure, but the copolymers of methylvinylidene cyanide are rich in alternating structure and might contain a minor part of poly(substituted styrene) as blocks or as homopolymers. A distinction between the two possibilities was not possible.     

Influence of prostaglandins on unidirectional zinc fluxes across the small intestine of the rat

1. The regulatory role of prostaglandins (PGs) E2 and F2 alpha on the zinc transport rate across the jejunal segments of rats was examined by employing the Ussing chamber technique. The Zn flux rate from mucosa to serosa across jejunal segments (Jms) was 5.24 (SE 1.54) nmol/h per cm2 (n 48) and that from serosa to mucosa (Jsm) was 15.16 (SE 2.38) nmol/h per cm2 (n 48) when both sides of the segment were bathed with Ringer's bicarbonate solution containing 0.5 mM-zinc chloride and 3 mM-L-histidine. 2. When 5.0 or 50 microM of either PGE2 or PGF2 alpha were added to the serosal side of the tissue, Jsm generally decreased and Jms generally increased, compared with controls. On the other hand, when PGE2 or PGF2 alpha was added to the mucosal side of the tissue, Jms either did not change or increased while Jsm had a tendency to decrease. 3. The Zn uptake capacity of tissue increased significantly when PG was added to the serosal side of the tissue-bathing medium, but not when PG was added to the mucosal side. The uptake capacity of mucosal Zn by jejunal segments was approximately twice that of serosal Zn. 4. When PG was included in the tissue-bathing medium, the short-circuit current, potential difference and conductance between the mucosa- and serosa-bathing media generally decreased. 5. These results suggest that (a) PGs influence Zn flux rate not by chelating Zn and carrying it across the mucosal cell membrane but by interacting with the cytosolic components, (b) it is the serosal PGs which control the Zn flux rate and (c) PGs play a part in triggering a transduction mechanism in the intestinal Zn transport process.     

Effect of bile acids and pH on the release of enteropeptidase in man

Bile acids increase the release of human enteropeptidase as well as other brush-border enzymes (alkaline phosphatase, leucine aminopeptidase) from duodenal mucosa, as had been shown earlier in experimental animals. The action of bile acids is independent of their known enhancing effect on enteropeptidase activity. The pH of duodenal juice is an important, hitherto unrecognized, factor in the release mechanism of brush-border enzymes. All of the above enzymes tested were released to a markedly greater extent at pH 8.2 than 6.3, regardless of the presence or absence of bile acid. Contrary to some results obtained with animal tissue, by other investigators, our experiments with human duodenal mucosa indicate that enteropeptidase, under all conditions tested, is released at a rate considerably greater than that for alkaline phosphatase or leucine aminopeptidase. The looser association of enteropeptidase with cellular components relative to that of other brush-border enzymes, as indicated by our observations, may be related to the unique function of enteropeptidase as the trigger enzyme of protein digestion.This work was supported by the Medical Research Service of the Veterans Administration.     

Congenital diverticulum of the tracheal carina in neonates. A case report].

A 17 day-old neonate with no history of broncho-pulmonary disease presented with a severe respiratory distress which was found to be related to a congenital tracheal diverticulum. An excision of the diverticulum was performed. Histologically it was characterized by a lining wall of stratified columnar ciliated epithelium and the presence of smooth muscle and cartilage in the wall. This rare entity was reported only once in the pediatric literature. It gives a history of chronic respiratory tract infections or acute respiratory distress. Bronchoscopy or bronchography and CT scan are necessary for the diagnosis. The treatment is surgical.     

Genomic analyses lead to novel secondary metabolites. Part 3. ECO-0501, a novel antibacterial of a new class

Genomic analyses of Amycolatopsis orientalis ATCC 43491 strain, deposited as a vancomycin producer, revealed the presence of genetic loci for the production of at least 10 secondary metabolites other than vancomycin. One of these gene clusters, which contained a type I polyketide synthase, was predicted to direct the synthesis of novel class of compound, a glycosidic polyketide ECO-0501 (1). Screening of culture extracts for a compound with the predicted physicochemical properties of the product from this locus, led to the isolation of the 13-O-glucuronide of 13-hydroxy-2,12,14,16,22-pentamethyl-28-(N-methyl-guanidino)-octacosa-2,4,6,8,10,14,20,24-octaenoic acid (2-hydroxy-5-oxo-cyclopent-1-enyl)-amide (ECO-0501, 1). The structure, confirmed by spectral analyses including MS, and ID and 2D NMR experiments, were in accord with that predicted by genomic analyses. ECO-0501 possessed strong antibacterial activity against a series of Gram-positive pathogens including several strains of methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococci (VRE). ECO-0501 was chemically modified by esterification (1a-1c), N-acetylation (1d) and hydrogenation (1e) in order to explore structure activity relationships (SAR).     

Elevated serum trypsin binding activity in patients with hereditary pancreatitis

Summary A new kindred with a high incidence of hereditary pancreatitis has been described. Five members (3 males and 2 females) are definitely affected and 2 others are suspected of having the disease. The laboratory finding of interest is a twofold increase in the serum trypsin binding activity in 2 of 3 affected members—despite the fact that their serum ₂-macroglobulin levels were within the normal range. The biological significance of this finding is not yet known. Recurrent attacks of abdominal pain began in early childhood in all affected members. Pancreatic calcifications are present in 3 members and diabetes mellitus and steatorrhea in 2 persons. Aminoaciduria was sought for in 2 members but was not found. None of the affected members had evidence of hyperlipemia or cholclithiasis or hyperparathyroidism, nor is any of them either a sporadic or a chronic alcoholic. Although the disease is reported to be transmitted as an autosomal dominant trait, incomplete penetrance or recessiveness are very likely mechanisms.Supported by Grants AM 08293-03 and AM 04683-06 from the U. S. Public Health Service.