Der Einfluss sogenannter Ovulationshemmer auf die Esteraseaktivität des Endometriums

Summary Histochemical investigations were carried out in the endometrium of guinea-pigs after administration of Anovlar (4 mg ethinylnortestosterone-acetate and 0.05 mg ethynylestradiol). Histochemically a decrease of non-specific esterase activity was found in the endometrial as well as in the glandular epithelium after Anovlar treatment. The relationship of this enzyme to synthetic steroid hormones is briefly discussed.     

The influence of peripheral or central administration of ondansetron on stress-induced gastric ulceration in rats

Ondansetron (0.08, 0.15 or 0.3 mg/kg) injected s.c., every 12h with the fourth dose given 0.5 h before experiments, dose-dependently lessened gastric glandular mucosal ulceration produced by cold-restraint stress for 2h. When given intracerebrally (i.c.) (0.1, 0.5 or 1g), using the same treatment regimen, infusion of ondansetron 1 g into the nucleus amygdaloideus centralis decreased stress-evoked ulcers; in contrast, injection of the same dose into the nucleus accumbens intensified these lesions. The associated stress-induced stomach wall mast cell degranulation was unaffected by all s.c. or i.c. doses of ondansetron. Pretreatment with disodium cromoglycate i.p. alone, or concurrently with ondansetron s.c., prevented not only ulceration but also mast cell degranulation. 5-Hydroxytryptamine₃ receptor antagonism appears to inhibit stress-evoked ulcers mainly by blocking the peripheral effects of the amine after its release from the gastric mucosal mast cells.     

Hotspots of homologous recombination

Homologous recombination occurs at higher than average frequency at and near hotspots. Hotspots are special nucleotide sequences recognized by proteins that promote, directly or indirectly, a rate limiting step of recombination. This review focuses on two well-studied examples, the Chi sites of the bacteriumEscherichia coli and the M26 site of the fission yeastSchizosaccharomyces pombe. Chi, 5 G-C-T-G-G-T-G-G 3, is recognized by the RecBCD enzyme, which nicks the DNA near Chi and produces a 3-ended single-stranded DNA tail; this tail is a potent substrate for homologous pairing by RecA and single-stranded DNA binding proteins. M26, 5 A-T-G-A-C-G-T 3, is recognized by a heterodimeric protein and stimulates, by an as-yet-unknown mechanism, meiotic recombination at and near theade6 gene. Additional hotspots in bacteria, fungi, and mammals enhance recombination directly or indirectly via a variety of mechanisms. Although hotspots are widespread among organisms, the biological role of their localized enhancement of recombination remains a matter of speculation.     

An investigation of the interaction between isoniazid and the contraceptive steroid norethindrone in vivo

Summary Isonicotinic acid hydrazide (isoniazid) was shown to react readily with 17-ethinyl-17-hydroxyestr-4-en-3-one (norethindrone) to form the isonicotinyl hydrazone of the steroid under conditions likely to exist in the stomach. The hydrazone was detected in guinea-pig, but not rat, plasma following its oral administration. Rat liver tissue metabolized the compound more rapidly than guinea-pig liver in vitro which probably accounts for the failure to detect the hydrazone in rat plasma.     

The animal musks and a comment of their biogenesis

Summary The macrocyclic compounds occurring in animal glandular secretions are reviewed. Early hypotheses for their biogenesis from fatty acids via and -oxidations are found to be inadequate. Radio-active acetate was incorporated into macrocyclic ketones of muskrat (Ondatra sp.) preputial glandular secretion, but radiolabelled stearate, oleate, anda, -octadecandioic acid were not incorporated.Acknowledgment. We wish to thank Dr.W.J. Doude van Troostwijk, Research Institute for Nature Management, Arnhem, for his assistance in obtaining muskrats, and Mr J. Vellekoop, Leiden, for the Shakespeare quotations.     

In vitro reconstitution of homologous recombination reactions

The proteins essential to homologous recombination inE. coli have been purified and their individual activities have been identified, permitting biochemical reconstitution of steps that comprise the cellular recombination process. This review focuses on the biochemical events responsible for the initiation and homologous pairing steps of genetic recombination. The properties of an in vitro recombination reaction that requires the concerted action of recA, recBCD, and SSB proteins and that is stimulated by the recombination hotspot, Chi(), are described. The recBCD enzyme serves as the initiator of this reaction; its DNA helicase activity produces single-stranded DNA that is used by the recA protein to promote homologous pairing and DNA strand invasion of supercoiled (recipient) DNA. The SSB protein acts to trap the single-stranded DNA produced by recBCD enzyme and to facilitate pairing by the recA protein. The regulatory sequence acts incis by attenuating the nuclease, but not the helicase, activity of recBCD enzyme. This attenuation assures the preservation of ssDNA produced by the DNA helicase activity and is responsible for the simulation in vitro and, presumably, in vivo. The attenuation of nuclease activity by results in the loss or functional inactivation of the recD subunit.     

Polarity of meiotic gene conversion in fungi: Contrasting views

The frequency of meiotic gene conversion often varies linearly from one end of the gene to the other. This phenomenon has been called polarity. In this review, we will primarily discuss studies of polarity that have been done in the yeastSaccharomyces cerevisiae (ARG4 and HIS4 loci) and inAscobolus (b2 locus) with an emphasis on possible mechanisms. The genetic and physical data obtained at these hotspots of recombination strongly suggests that the formation of a polarity gradient reflects both the frequency of heteroduplex formation and the processing of this recombination intermediate by mismatch-repair-dependent processes.This article is dedicated to the memory of Seymour Fogel.     

Immunological blocking of exogenous and endogenous secretin in the dog

Summary In mongrel dogs with chronic gastric and duodenal fistula the biological activity of secretin on exocrine pancreatic secretion could be blocked by preincubating the secretin injected with rabbit antisecretin antibody. In addition, the activity of endogenous secretin released by acid was markedly reduced by application of antibody. Since no such effect was observed after testmeal stimulation, secretin is most probably not released in a significant amount by the liquid meal used in this experiment.This work was supported by grant No. 3.816-0.76 of the Swiss National Foundation for Scientific Research.We express our thanks to Miss G. van Hees, Mrs L. Jecker and Dr F. Meyer for their excellent technical assistance, Dr W. W. Rittmann for the surgical support, Dr G.A. Stalder for general advice, Dres R. Studer and D. Gillessen for providing secretin Roche, and Mrs C. Frei for secretarial work.     

Effect of α- and β-ecdysone on DNA synthesis inAeshna cyanea (Insecta,Odonata) midgut

Summary InAeshna cyanea larvae, - and -ecdysone stimulate DNA synthesis in the midgut regenerative cells. In last larval instar, the number of cells obtained after the imaginal epithelium genesis is greater after - than after -ecdysone supply. Such a result should be compared with the imaginal epithelium differentiation which occurs earlier after -ecdysone injection.     

Refeeding of mice after fasting stimulates cell renewal in the gall bladder epithelium

Summary The effect of refeeding of mice after a fasting period on the uptake of 3H-thymidine and on mitotic activity in the gall bladder epithelium was studied by histoautoradiography. A significant increase in both DNA synthesis and mitotic activity was observed after 12 h of refeeding.Acknowledgments. This work was supported by the Fonds voor Geneeskundig Wetenschappelijk Onderzoek and by the Algemeene Spar-en Lijfrentekas.     

The effect of caerulein on epithelial growth in the mouse gall bladder

Summary Caerulein, a synthetic decapeptide, was injected into mice in order to study its effect on DNA-synthesis activity in the gall bladder epithelium. Histoautoradiography after the injection of labeled thymidine was used. Higher labeling indices were observed at 8, 12 and 24 h after caerulein injection. These data indicate that caerulein, apart from its cholecystokinetic effects, exerts a trophic effect on the gall bladder mucosa.Acknowledgements: this work was supported in part by the Fonds voor Geneeskundig Wetenschappelijk Onderzoek and by the Algemene Spaar- en Lijfrentekas.     

X-ray microanalysis in pearls ofMytilus edulis L. (bivalvia)

Summary Metacercariae feeding on the tissues of Mytilus edulis deposit their excretes into the mussel. The clusters of excretes are surrounded by a pearl sac. Increasing amounts of Ca-proteids are transported into the pearl sac epithelium and into the pearl.     

A simple method for in vivo testing of glandular enzymatic activity on potential precursors of larval defensive compounds inPhratora species (Coleoptera: Chrysomelinae)

The presence of glandular -glucosidase and oxidase-specific activities, and the possible role of phenolglucosides and related compounds as precursors for larval defensive compounds, were directly demonstrated by introducing salicin, saligenin and helicin into the defensive glands ofPhratora species.Ph. tibialis andPh. laticollis that normally secrete endogenously-produced iridoid monoterpenes and do not use phenolglucosides from their food sources as precursors, were able to produce salicyladehyde from helicin when the latter was introduced into the defensive glands.     

Physicochemical studies of indocyanine green (ICG): absorbance/concentration relationship,pH tolerance and assay precision in various solvents

Summary Indocyanine green (ICG) obeyed the Beer-Lambert law within the concentration range 1.25 g/ml–10.0g/ml in distilled water, methanol, dimethylformamide (DMF), 1.2-propanediol and aqueous buffers (pH 9.0), but only up to 7.5 g/ml in human bile and 0.5% human albumin, and only to 5.0 g/ml in human duodenal fluid. ICG was rapidly (<1 h) decomposed to a colorless derivative at pH<5 and >11, but remained relatively stable for 48 h at pH 8–10. ICG is an indicator and a weak acid with a pKa of 3.27. In bile stabilized with 25% methanol, the precision of the method (CV) is 5% and the accuracy is 106–127%.     

A novel exocrine gland inside the thoracic appendages (‘gemmae’) of the queenless antDiacamma australe

Summary In the queenless antDiacamma australe, all workers eclose with a pair of tiny thoracic appendages (gemmae). These are sac-like and exhibit a distinct cuticular sculpturing, with minute pores opening on the outer surface. These pores are connected to glandular cells which completely fill the appendages, and thus an exocrine stignal is likely to be released. We discuss the social context of this signal: only one worker in each colony retains the gemmae.     

Morphogenesis of human colon cancer cells with fetal rat mesenchymes in organ culture

The morphogenesis and cytodifferentiation of human colon cancer cells (LS174T and HT29) were examined by combining cancer cells with fetal rat digestive-tract mesenchyme in organ culture. LS174T cells migrated into the mesenchyme to form glandular structures composed of single columnar cells with their nuclei oriented basally, while HT29 cells formed cell masses with little lumen formation. Immunohistochemical studies with antibodies against carcinoembryonic antigen and secretory components showed that the composition of cell surface glycoproteins was not necessarily reversed to the normal type, even when neoplastic cells exhibited normal glandular structures.     

Bobierrit-Newberyit-Konkremente in den Drüsensäckchen des Vormagens vonLama lama

Summary The formation of Bobierrite/Newberyiteconcrements may occur in the glandular saccules of the llama (Lama lama) forestomach, if the motility of abomasal compartments is disturbed and these saccules are not able to evert at periodic intervals.     

Electron microscopy of gastric mucosal innervation in rats

Summary Electron microscopy of the rat stomach has shown vagal innervation of gastric epithelial cells with contact points. Unmyelinated axons of diameter 0.06 and 0.20 m were demonstrated passing in the connective tissue between epithelial cells.     

Binding of 11-cis retinaldehyde to the partially purified cellular retinaldehyde binding protein from bovine retinal pigment epithelium

Summary 11-cis retinaldehyde binding analysis was performed on a bovine retinal pigment epithelium preparation of cellular retinaldehyde binding protein (CRALBP), whose purity degree was estimated as 75%. Equilibrium binding studies were carried out measuring the replacement of tritium-labeled with unlabeled 11-cis retinaldehyde at 25°C. Analysis of the experimental data both by a direct curve-fitting procedure utilizing a non linear least square regression analysis and by a conventional Scatchard plot revealed a single non-interacting binding site with an apparent equilibrium constant of 0.9×10^–7 M.A binding stoichiometry of approximately 1 mol of 11-cis retinaldehyde/mol of binding protein can be calculated from the experimental data. Competition studies carried out in the presence of unlabeled trans and cis isomers of Vitamin A derivatives confirm the high degree of specificity of the 11-cis retinaldehyde binding.     

Morphogenesis of human colon cancer cells with fetal rat mesenchymes in organ culture

Summary The morphogenesis and cytodifferentiation of human colon cancer cells (LS174T and HT29) were examined by combining cancer cells with fetal rat digestive-tract mesenchyme in organ culture. LS174T cells migrated into the mesenchyme to form glandular structures composed of single columnar cells with their nuclei oriented basally, while HT29 cells formed cell masses with little lumen formation. Immunohistochemical studies with antibodies against carcinoembryonic antigen and secretory components showed that the composition of cell surface glycoproteins was not necessarily reversed to the normal type, even when neoplastic cells exhibited normal glandular structures.This work was supported by grants-in-aid for Cancer Research from the Ministry of Education, Science, and Culture, Japan, and by the Veterans Administration Medical Research Service, USA. Y.S. Kim is the recipient of a Medical Investigator Award of the Veterans Administration.