Synthesis and biological activity of glycosylated analogs of somatostatin

The synthesis by solid-phase methodology of two glycosylated analogs of somatostatin [Glc-Asn⁵]-SS and [NAcGlc-Asn⁵]-SS is described. These two analogs have been biologically tested on the secretion of pituitary growth hormone, pancreatic glucagon and insulin. The results show that glycosylation of somatostatin on the Asn⁵ residue decreases by a hundred fold the inhibition activity on GH release when tested $\text{in}$$\text{vitro}$. $\text{In}$$\text{vivo}$, since the activity is similar to somatostatin the carbohydrates are probably removed by some enzymatic reaction and thus liberate the full activity of somatostatin.     

N-Acetylaminoacyl-p-nitranilidase from human placenta. Purification and some properties.

An enzyme hydrolyzing N-acetylaminoacyl-p-nitroanilides has been isolated from mature human placentae by a six-step procedure comprising extraction from a placenta homogenate, ammonium sulfate fractionation, treatment with isopentyl alcohol, chromatography on CM-Sephadex, protamine sulfate precipitation and gel filtration on an Ultrogel AcA 34 column. About 2500-fold enrichement was achieved from placenta homogenate. The purified enzyme preparation showed a single band on polyacrylamide disc electrophoresis. The molecular weight was estimated to be 380,000 by gel filtration. Placental extracts contain two main isoenzymes of pI 3.9 and 4.5 respectively. Activity was strongly inhibited by chloromercuribenzoate, slightly inhibited by Ca2+ and cysteine; no activation could be detected. The enzyme exhibits an exopeptidase-like activity towards acetyl-dipeptides with a certain specifity towards N-acetylalanyl-alanine; N-acetylalanine-p-nitroanilide, however, is hydrolyzed four times faster. With N-acetylalanine-p-nitroanilide as substrate the pH optimum was 8.0--8.2; Km was 2.13 mmol/l. N-Acetylleucine-p-nitroanilide and N-acetyltyrosine-p-nitroanilide were split slowly; N-acetylalanyl-alanyl-alanine-p-nitroanilide, N-butyloxycarbonyl-alanyl-alanine-p-nitroanilide, unsubstituted analogous aminoacyl-p-nitroanilides and several protein substrates were not hydrolyzed. The functions of the enzyme are still unknown.     

The influence of coal ash and thermal discharges upon the distribution and bioaccumulation of aquatic invertebrates

The distribution, density and uptake of twenty elements by aquatic invertebrates inhabiting a drainage system, that received excessive coal ash effluent (275 JTU of turbidity) at one end and thermal loading (44.5°C) at the other end, was studied for 15 months. The ash settling basin filled during the first eight months of sampling which resulted in the release of ash effluent directly into the receiving system. Density of invertebrates was lowest in the 300 m stream between the ash basin and swamp and highest 1200 m beyond the stream-swamp confluence where ash influence was minimal. Invertebrate density was lowest in the stations where turbidity from ash effluent was greatest. The most tolerant invertebrates to coal ash stress were odonates (Libellula sp. and Enallagma sp.), crayfish (Procambarus sp.), amphipods (Gammarus sp.) and gastropods (Physa. sp.), and midges (Chironomidae) when the basin was filling. During the period of ash overflow, all groups were either reduced in numbers or absent. In the thermally stressed station, Libellula sp. was the predominant invertebrate sampled when water temperature ranged from 25.5–45.5°C (257-1=28.7°C) all aquatic invertebrates were limited in numbers and density when temperature exceeded the lower and upper ranges of 10.0–38.0°C.This research was supported by AEC Contract AT (38-1-824)This research was supported by AEC Contract AT (38-1-824)     

Pyronaridine–artesunate real-world safety,tolerability, and effectiveness in malaria patients in 5 African countries: A single-arm,open-label,cohort event monitoring study

BackgroundIn Phase II/III randomized controlled clinical trials for the treatment of acute uncomplicated malaria, pyronaridine–artesunate demonstrated high efficacy and a safety profile consistent with that of comparators, except that asymptomatic, mainly mild-to-moderate transient increases in liver aminotransferases were reported for some patients. Hepatic safety, tolerability, and effectiveness have not been previously assessed under real-world conditions in Africa.Methods and findingsThis single-arm, open-label, cohort event monitoring study was conducted at 6 health centers in Cameroon, Democratic Republic of Congo, Gabon, Ivory Coast, and Republic of Congo between June 2017 and April 2019. The trial protocol as closely as possible resembled real-world clinical practice for the treatment of malaria at the centers. Eligible patients were adults or children of either sex, weighing at least 5 kg, with acute uncomplicated malaria who did not have contraindications for pyronaridine–artesunate treatment as per the summary of product characteristics. Patients received fixed-dose pyronaridine–artesunate once daily for 3 days, dosed by body weight, without regard to food intake. A tablet formulation was used in adults and adolescents and a pediatric granule formulation in children and infants under 20 kg body weight. The primary outcome was the hepatic event incidence, defined as the appearance of the clinical signs and symptoms of hepatotoxicity confirmed by a >2× rise in alanine aminotransferase/aspartate aminotransferase (ALT/AST) versus baseline in patients with baseline ALT/AST >2× the upper limit of normal (ULN). As a secondary outcome, this was assessed in patients with ALT/AST >2× ULN prior to treatment versus a matched cohort of patients with normal baseline ALT/AST. The safety population comprised 7,154 patients, of mean age 13.9 years (standard deviation (SD) 14.6), around half of whom were male (3,569 [49.9%]). Patients experienced 8,560 malaria episodes; 158 occurred in patients with baseline ALT/AST elevations >2×ULN. No protocol-defined hepatic events occurred following pyronaridine–artesunate treatment of malaria patients with or without baseline hepatic dysfunction. Thus, no cohort comparison could be undertaken. Also, as postbaseline clinical chemistry was only performed where clinically indicated, postbaseline ALT/AST levels were not systematically assessed for all patients. Adverse events of any cause occurred in 20.8% (1,490/7,154) of patients, most frequently pyrexia (5.1% [366/7,154]) and vomiting (4.2% [303/7,154]). Adjusting for Plasmodium falciparum reinfection, clinical effectiveness at day 28 was 98.6% ([7,369/7,746] 95% confidence interval (CI) 98.3 to 98.9) in the per-protocol population. There was no indication that comorbidities or malnutrition adversely affected outcomes. The key study limitation was that postbaseline clinical biochemistry was only evaluated when clinically indicated.ConclusionsPyronaridine–artesunate had good tolerability and effectiveness in a representative African population under conditions similar to everyday clinical practice. These findings support pyronaridine–artesunate as an operationally useful addition to the management of acute uncomplicated malaria.Trial registrationClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT03201770","term_id":"NCT03201770"}}NCT03201770.

Gaston Tona Lutete and co-workers report on safety and effectiveness of the antimalarial drug pyronaridine-artesunate in African countries.     

Tandem-repetitive noncoding DNA: forms and forces

A model of sequence-dependent, unequal crossing-over and gene amplification (slippage replication) has been stimulated in order to account for various structural features of tandemly repeated DNA sequences. It is shown that DNA whose sequence is not maintained by natural selection will exhibit repetitive patterns over a wide range of recombination rates as a result of the interaction of unequal crossing-over and slippage replication, processes that depend on sequence similarity. At high crossing-over frequencies, the nucleotide patterns generated in the simulations are simple and highly regular, with short, nearly identical sequences repeated in tandem. Decreasing recombination rates increase the tendency to longer and more-complex repeat units. Periodicities have been observed down to very low recombination rates (one or more orders of magnitude lower than mutation rate). At such low rates, most of the sequences contain repeats which have an extensive substructure and a high degree of heterogeneity among each other; often higher-order structures are superimposed on a tandem array. These results are compared with various structural properties of tandemly repeated DNAs known from eukaryotes, the spectrum ranging from simple-sequence DNAs, particularly the hypervariable mini-satellites, to the classical satellite DNAs, located in chromosomal regions of low recombination, e.g., heterochromatin.     

Purine nucleoside phosphorylase (Np) in the mouse: Linkage relationship of Np-2 to esterase-10 (Es-10) and Np-1 on chromosome 14

An improved method for detecting four Np-1 (purine nucleoside phosphorylase) alleles in mouse erythrocytes by cellulose acetate electrophoresis is described. The previous linkage of Np-1 and Es-10 (esterase-10) was confirmed, with a map distance of 13.0±2.6 cM. Np-2 was detected by either specific activity assay or starch gel electrophoresis and shown to be linked to Es-10, 15.9 ± 3.1 cM, on chromosome 14. No recombinants between Np-1 and Np-2 were observed in 52 offspring, indicating either that these loci are either closely associated or that Np-2 represents simply a property of existing allelic products of the Np-1 locus.This research was supported by Medical Research Council of Canada grants to F.G.B. and F.F.S.     

Properties of immunoreactive glucagon fractions of canine stomach and pancreas.

The present study was designed to identify the physicochemical, immunologic, and biologic properties of the immunoreactive glucagon (IRG) moieties of canine gastric fundus and to compare them with those of the canine pancreas. Acid-alcohol extracts of the gastric fundus and pancreas of dogs were subjected to Bio-Gel P-10 chromatography, The elution profiles of extracts of both organs revealed IRG peaks in the Mr = 2,000 3,500, and 9,000 zones; in the gastric extracts, a void volume peak was also present. On the basis of Sephadex G-150 rechromatography and sucrose density gradient ultracentrifugation the latter IRG was estimated to have a Mr = 65,000. Incubation of fundic IRG65,000 in 8 M urea failed to alter its elution position. Its pI was 6.4, while fundic IRG3,500 had a pI of 6.15 and pancreatic glucagon 6.25.Fundic IRG9,000 had a pI of 4.5 and pancreatic IRG9,000 4.65. Dilution curves of these three fundic and two pancreatic IRGs were parallel to crystalline beef-pork glucagon. The glycogenolytic activity of fundic IRG3,500 and IRG65,000, measured in the isolated rat liver system, was not different from that of immunoequivalent amounts of dog pancreatic glucagon or crystalline beef-pork glucagon. Both fundic and pancreatic IRG9,000 were devoid of glycogenolytic activity and lacker adenylate cyclase stimulating activity and 125I-glucagon displacing activity when tested on partially purified rat liver membranes. Fundic IRG65,000, however, stimulated adenylate cyclase and displaced 125I-glucagon to the same degree as immunoequivalent amounts of pancreatic glucagon. Fundic IRG3,500 was more active than pancreatic glucagon in stimulating adenylate cyclase activity. This was not clearly attributable to differences in binding to liver cell membranes.