Structure Revision of a Widespread Marine Sulfonolipid Class Based on Isolation and Total Synthesis

The cosmopolitan marine Roseobacter clade is of global biogeochemical importance. Members of this clade produce sulfur-containing amino lipids (SALs) involved in biofilm formation and marine surface colonization processes. Despite their physiological relevance and abundance, SALs have only been explored through genomic mining approaches and lipidomic studies based on mass spectrometry, which left the relative and absolute structures of SALs unresolved, hindering progress in biochemical and functional investigations. Herein, we report the structural revision of a new group of SALs, which we named cysteinolides, using a combination of analytical techniques, isolation and degradation experiments and total synthetic efforts. Contrary to the previously proposed homotaurine-based structures, cysteinolides are composed of an N,O-acylated cysteinolic acid-containing head group carrying various different (α-hydroxy)carboxylic acids. We also performed the first validated targeted-network based analysis, which allowed us to map the distribution and structural diversity of cysteinolides across bacterial lineages. Beyond offering structural insight, our research provides SAL standards and validated analytical data. This information holds significance for forthcoming investigations into bacterial sulfonolipid metabolism and biogeochemical nutrient cycling within marine environments.

Nonribosomal peptides protect Pseudomonas nunensis 4A2e from amoebal and nematodal predation

The rhizosphere is a highly competitive environment forcing bacteria to evolve strategies to oppose their enemies. The production of toxic secondary metabolites allows bacteria to counteract predators. In this study, we describe the anti-predator armamentarium of the soil-derived bacterium Pseudomonas nunensis 4A2e. Based on a genome mining approach, we identified several biosynthetic gene clusters coding for nonribosomal peptide synthetases. Generation of gene deletion mutants of the respective clusters shows a loss of defense capabilities. We isolated the novel lipopeptides keanumycin D and nunapeptins B and C, and fully elucidated their structures by a combination of in-depth mass spectrometry experiments, stable isotope labelling, and chemical synthesis. Additionally, investigation of the quorum sensing-dependent biosynthesis allowed us to elucidate parts of the underlying regulation of the biosynthetic machinery. Ecology-inspired bioassays highlight the role of these peptides as a defence strategy against protozoans and led us to find a previously unknown function against the bacterivorous nematode Oscheius myriophilus.

Ecological Niche-Inspired Genome Mining Leads to the Discovery of Crop-Protecting Nonribosomal Lipopeptides Featuring a Transient Amino Acid Building Block

Investigating the ecological context of microbial predator-prey interactions enables the identification of microorganisms, which produce multiple secondary metabolites to evade predation or to kill the predator. In addition, genome mining combined with molecular biology methods can be used to identify further biosynthetic gene clusters that yield new antimicrobials to fight the antimicrobial crisis. In contrast, classical screening-based approaches have limitations since they do not aim to unlock the entire biosynthetic potential of a given organism. Here, we describe the genomics-based identification of keanumycins A-C. These nonribosomal peptides enable bacteria of the genus Pseudomonas to evade amoebal predation. While being amoebicidal at a nanomolar level, these compounds also exhibit a strong antimycotic activity in particular against the devastating plant pathogen Botrytis cinerea and they drastically inhibit the infection of Hydrangea macrophylla leaves using only supernatants of Pseudomonas cultures. The structures of the keanumycins were fully elucidated through a combination of nuclear magnetic resonance, tandem mass spectrometry, and degradation experiments revealing an unprecedented terminal imine motif in keanumycin C extending the family of nonribosomal amino acids by a highly reactive building block. In addition, chemical synthesis unveiled the absolute configuration of the unusual dihydroxylated fatty acid of keanumycin A, which has not yet been reported for this lipodepsipeptide class. Finally, a detailed genome-wide microarray analysis of Candida albicans exposed to keanumycin A shed light on the mode-of-action of this potential natural product lead, which will aid the development of new pharmaceutical and agrochemical antifungals.

Correction: Tyrosine bioconjugation with hypervalent iodine

[This corrects the article DOI: 10.1039/D2SC04558C.].

Tyrosine bioconjugation with hypervalent iodine

Hypervalent iodine reagents have recently emerged as powerful tools for late-stage peptide and protein functionalization. Herein we report a tyrosine bioconjugation methodology for the introduction of hypervalent iodine onto biomolecules under physiological conditions. Tyrosine residues were engaged in a selective addition onto the alkynyl bond of ethynylbenziodoxolones (EBX), resulting in stable vinylbenziodoxolones (VBX) bioconjugates. The methodology was successfully applied to peptides and proteins and tolerated all other nucleophilic residues, with the exception of cysteine. The generated VBX were further functionalized by palladium-catalyzed cross-coupling and azide-alkyne cycloaddition reactions. The method could be successfully used to modify bioactive natural products and native streptavidin to enable thiol-mediated cellular uptake.

Frame-by-Frame Analysis of a Commercially Available Artificial Intelligence Polyp Detection System in Full-Length Colonoscopies

INTRODUCTION

Computer-aided detection (CADe) helps increase colonoscopic polyp detection. However, little is known about other performance metrics like the number and duration of false-positive (FP) activations or how stable the detection of a polyp is.

METHODS

111 colonoscopy videos with total 1,793,371 frames were analyzed on a frame-by-frame basis using a commercially available CADe system (GI-Genius, Medtronic Inc.). Primary endpoint was the number and duration of FP activations per colonoscopy. Additionally, we analyzed other CADe performance parameters, including per-polyp sensitivity, per-frame sensitivity, and first detection time of a polyp. We additionally investigated whether a threshold for withholding CADe activations can be set to suppress short FP activations and how this threshold alters the CADe performance parameters.

RESULTS

A mean of 101 ± 88 FPs per colonoscopy were found. Most of the FPs consisted of less than three frames with a maximal 66-ms duration. The CADe system detected all 118 polyps and achieved a mean per-frame sensitivity of 46.6 ± 26.6%, with the lowest value for flat polyps (37.6 ± 24.8%). Withholding CADe detections up to 6 frames length would reduce the number of FPs by 87.97% (p < 0.001) without a significant impact on CADe performance metrics.

CONCLUSIONS

The CADe system works reliable but generates many FPs as a side effect. Since most FPs are very short, withholding short-term CADe activations could substantially reduce the number of FPs without impact on other performance metrics. Clinical practice would benefit from the implementation of customizable CADe thresholds.

Total Synthesis and Structure Correction of the Cyclic Lipodepsipeptide Orfamide A

A total synthesis of the cyclic lipodepsipeptide natural product orfamide A was achieved. By developing a synthesis format using an aminoacid ester building block and SPPS protocol adaptation, a focused library of target compounds was obtained, in high yield and purity. Spectral and LC‐HRMS data of all library members with the isolated natural product identified the ⁵Leu residue to be d‐ and the 3’‐OH group to be R‐configured. The structural correction of orfamide A by chemical synthesis and analysis was confirmed by biological activity comparison in Chlamydomonas reinhardtii, which indicated compound configuration to be important for bioactivity. Acute toxicity was also found against Trypanosoma brucei, the parasite causing African sleeping sickness.

Discovery of a Small-Molecule-Dependent Photolytic Peptide

We accidentally found that YM-53601, a known small-molecule inhibitor of squalene synthase (SQS), selectively depletes SQS from mammalian cells upon UV irradiation. Further analyses indicated that the photodepletion of SQS requires its short peptide segment located at the COOH terminus. Remarkably, when the 27 amino acid peptide was fused to green fluorescent protein or unrelated proteins at either the NH₂ or COOH terminus, such fusion proteins were selectively depleted when the cells were treated with both YM-53601 and UV exposure. Product analysis and electron spin resonance experiments suggested that the UV irradiation promotes homolytic C-O bond cleavage of the aryl ether group in YM-53601. It is likely that the radical species generated from UV-activated YM-53601 abstract hydrogen atoms from the SQS peptide, leading to the photolysis of the entire protein. The pair of the SQS peptide and YM-53601 discovered in the present study paves the way for the design of a new small-molecule-controlled optogenetic tool.

Structure elucidation of bacterial nonribosomal lipopeptides

We provide a summary of the tools, which allow elucidate the structures of nonribosomal lipopetides.

Structure, properties, and biological functions of nonribosomal lipopeptides from pseudomonads

Bacteria of the genusPseudomonasdisplay a fascinating metabolic diversity. In this review, we focus our attention on the natural product class of nonribosomal lipopeptides, which help pseudomonads to colonize a wide range of ecological niches.

Structure elucidation of the syringafactin lipopeptides provides insight in the evolution of nonribosomal peptide synthetases

Modular biosynthetic machineries such as polyketide synthases (PKSs) or nonribosomal peptide synthetases (NRPSs) give rise to a vast structural diversity of bioactive metabolites indispensable in the treatment of cancer or infectious diseases. Here, we provide evidence for different evolutionary processes leading to the diversification of modular NRPSs and thus, their respective products. Discovery of a novel lipo-octapeptide family from Pseudomonas, the virginiafactins, and detailed structure elucidation of closely related peptides, the cichofactins and syringafactins, allowed retracing recombinational diversification of the respective NRPS genes. Bioinformatics analyses allowed us to spot an evolutionary snapshot of these processes, where recombination occurred both within the same and between different biosynthetic gene clusters. Our systems feature a recent diversification process, which may represent a typical paradigm to variations in modular biosynthetic machineries.

Bioactivity and Mode of Action of Bacterial Tetramic Acids

Microbially produced 3-acyltetramic acids display a diverse range of biological activities. The pyreudiones are new members of this class that were isolated from bacteria of the genus Pseudomonas. Here, we performed a structure-activity relationship study and determined their mode of action. An efficient biomimetic synthesis was developed to synthesize pyreudione A. Pyreudiones and synthetic analogs thereof were tested for their amoebicidal, antibacterial, antiproliferative, and cytotoxic activities. The length of the alkyl side chain and the nature of the amino acid residues within the tetramic acid moiety strongly affected activity, in particular against mycobacteria. The mode of action was shown to correlate with the ability of pyreudiones to act as protonophores. Removal of the acidic proton by methylation of pyreudione A resulted in a loss of bioactivity.

Synthesis, Liposomal Formulation, and Immunological Evaluation of a Minimalistic Carbohydrate-α-GalCer Vaccine Candidate

Fully synthetic glycan-based vaccines hold great potential as preventive and therapeutic vaccines against infectious diseases as well as cancer. Here, we present a two-component platform based on the facile conjugation of carbohydrate antigens to α-galactosylceramide (α-GalCer) to yield fully synthetic vaccine candidates. Formulation of the cancer-associated Tn antigen glycolipid model vaccine candidate into liposomes of different sizes and subsequent immunization of mice generated specific, high-affinity antibodies against the carbohydrate antigen with characteristics of T cell-dependent immunity. Liposome formulation elicited more reproducible glycan immunity than a conventional glycoconjugate vaccine bearing the same glycan antigen did. Further evaluation of the immune response revealed that the size of the liposomes influenced the glycan antibody responses toward either a cellular (Th1) or a humoral (Th2) immune phenotype. The glycolipid vaccine platform affords strong and robust antiglycan antibody responses in vivo without the need for an external adjuvant.

Structure, Biosynthesis, and Biological Activity of the Cyclic Lipopeptide Anikasin

The class of cyclic lipopeptide natural products consists of compounds with a diverse range of bioactivities. In this study, we elucidated the structure of the cyclic lipopeptide anikasin using X-ray crystallography, analyzed its biosynthetic gene cluster, and investigated its natural role in the interaction between the producer strain Pseudomonas fluorescens HKI0770 and protozoal predators. These results led to the conclusion that anikasin has dual functionality enabling swarming motility and acting as a niche amoebicide, which effectively inhibits the social amoeba Polysphondylium violaceum and protects the producer strain from protozoal grazing.

Investigation of Feshbach resonances in ultracold 40K spin mixtures

Magnetically tunable Feshbach resonances are an indispensable tool for experiments with atomic quantum gases. We report on 37 thus far unpublished Feshbach resonances and four further probable Feshbach resonances in spin mixtures of ultracold fermionic ⁴⁰K with temperatures well below 100 nK. In particular, we locate a broad resonance at B = 389.7G with a magnetic width of 26.7 G. Here 1 G = 10^-4 T. Furthermore, by exciting low-energy spin waves, we demonstrate a means to precisely determine the zero crossing of the scattering length for this broad Feshbach resonance. Our findings allow for further tunability in experiments with ultracold ⁴⁰K quantum gases.

Bacterial Alkaloids Prevent Amoebal Predation

Bacterial defense mechanisms have evolved to protect bacteria against predation by nematodes, predatory bacteria, or amoebae. We identified novel bacterial alkaloids (pyreudiones A-D) that protect the producer, Pseudomonas fluorescens HKI0770, against amoebal predation. Isolation, structure elucidation, total synthesis, and a proposed biosynthetic pathway for these structures are presented. The generation of P. fluorescens gene-deletion mutants unable to produce pyreudiones rendered the bacterium edible to a variety of soil-dwelling amoebae.

Beyond fibrosis: stellate cells as liver stem cells

The high regenerative potential of the liver is driven by parenchymal and non-parenchymal cells, which restore the original liver mass after injury by cell proliferation. The contribution of stem- and progenitor cells to liver regeneration is mainly observed when hepatocyte proliferation is impaired. However, the origin of stem/progenitor cells and their effectivity to restore injured liver is currently discussed controversially. Hepatic stellate cells, which are mainly known for their contribution to fibrosis in chronic liver diseases, were recently identified as mesenchymal stem cells (MSC) of the liver. Stellate cells are also involved in liver regeneration and fulfill a dual function by supporting neighboring cells and developing into liver epithelial cells. This demonstrates that stellate cells not only exhibit the same expression profile and differentiation potential but also functional similarities to MSC of other organs, which are at present intensively studied by many groups for their therapeutic use in liver diseases.

Defining the Interaction of Human Soluble Lectin ZG16p and Mycobacterial Phosphatidylinositol Mannosides

ZG16p is a soluble mammalian lectin that interacts with mannose and heparan sulfate. Here we describe detailed analysis of the interaction of human ZG16p with mycobacterial phosphatidylinositol mannosides (PIMs) by glycan microarray and NMR. Pathogen-related glycan microarray analysis identified phosphatidylinositol mono- and di-mannosides (PIM1 and PIM2) as novel ligand candidates of ZG16p. Saturation transfer difference (STD) NMR and transferred NOE experiments with chemically synthesized PIM glycans indicate that PIMs preferentially interact with ZG16p by using the mannose residues. The binding site of PIM was identified by chemical-shift perturbation experiments with uniformly (15)N-labeled ZG16p. NMR results with docking simulations suggest a binding mode of ZG16p and PIM glycan; this will help to elucidate the physiological role of ZG16p.

Investigation of the protective properties of glycosylphosphatidylinositol-based vaccine candidates in a Toxoplasma gondii mouse challenge model

Vaccination against the ubiquitous parasite Toxoplasma gondii would provide the most efficient prevention against toxoplasmosis-related congenital, brain and eye diseases in humans. We investigated the immune response elicited by pathogen-specific glycosylphosphatidylinositol (GPI) glycoconjugates using carbohydrate microarrays in a BALB/c mouse model. We further examined the protective properties of the glycoconjugates in a lethal challenge model using the virulent T. gondii RH strain. Upon immunization, mice raised antibodies that bind to the respective GPIs on carbohydrate microarrays, but were mainly directed against an unspecific GPI epitope including the linker. The observed immune response, though robust, was unable to provide protection in mice when challenged with a lethal dose of viable tachyzoites. We demonstrate that anti-GPI antibodies raised against the here described semi-synthetic glycoconjugates do not confer protective immunity against T. gondii in BALB/c mice.

Diagnosis of toxoplasmosis using a synthetic glycosylphosphatidylinositol glycan

Around 2 billion people worldwide are infected with the apicomplexan parasite Toxoplasma gondii which induces a variety of medical conditions. For example, primary infection during pregnancy can result in fetal death or mental retardation of the child. Diagnosis of acute infections in pregnant women is challenging but crucially important as the drugs used to treat T. gondii infections are potentially harmful to the unborn child. Better, faster, more reliable, and cheaper means of diagnosis by using defined antigens for accurate serological tests are highly desirable. Synthetic pathogen-specific glycosylphosphatidylinositol (GPI) glycan antigens are diagnostic markers and have been used to distinguish between toxoplasmosis disease states using human sera.

Intrinsic photoconductivity of ultracold fermions in optical lattices

We report on the experimental observation of an analog to a persistent alternating photocurrent in an ultracold gas of fermionic atoms in an optical lattice. The dynamics is induced and sustained by an external harmonic confinement. While particles in the excited band exhibit long-lived oscillations with a momentum-dependent frequency, a strikingly different behavior is observed for holes in the lowest band. An initial fast collapse is followed by subsequent periodic revivals. Both observations are fully explained by mapping the system onto a nonlinear pendulum.

Synthesis of carbohydrate-functionalised sequence-defined oligo(amidoamine)s by photochemical thiol-ene coupling in a continuous flow reactor

Poly/oligo(amidoamine)s (PAAs) have recently been recognised for their potential as well-defined scaffolds for multiple carbohydrate presentation and as multivalent ligands. Herein, we report two complimentary strategies for the preparation of such sequence-defined carbohydrate-functionalised PAAs that use photochemical thiol-ene coupling (TEC) as an alternative to the established azide-alkyne cycloaddition ("click") reaction. In the first approach, PAAs that contained multiple olefins were synthesised on a solid support from a new building block and subsequent conjugation with unprotected thio-carbohydrates. Alternatively, a pre-functionalised building block was prepared by using TEC and assembled on a solid support to provide a carbohydrate-functionalised PAA. Both methods rely on the use of a continuous flow photoreactor for the TEC reactions. This system is highly efficient, owing to its short path length, and requires no additional radical initiator. Performing the reactions at 254 nm in Teflon AF-2400 tubing provides a highly efficient TEC procedure for carbohydrate conjugation, as demonstrated in the reactions of O-allyl glycosides with thiols. This method allowed the complete functionalisation of all of the reactive sites on the PAA backbone in a single step, thereby obtaining a defined homogeneous sequence. Furthermore, reaction at 366 nm in FEP tubing in the flow reactor enabled the large-scale synthesis of an fluorenylmethyloxycarbonyl (Fmoc)-protected glycosylated building block, which was shown to be suitable for solid-phase synthesis and will also allow heterogeneous sequence control of different carbohydrates along the oligomeric backbone. These developments enable the synthesis of sequence-defined carbohydrate-functionalised PAAs with potential biological applications.

Multiband spectroscopy of ultracold fermions: observation of reduced tunneling in attractive Bose-Fermi mixtures

We perform a detailed experimental study of the band excitations and tunneling properties of ultracold fermions in optical lattices. Employing a novel multiband spectroscopy for fermionic atoms, we can measure the full band structure and tunneling energy with high accuracy. In an attractive Bose-Fermi mixture we observe a significant reduction of the fermionic tunneling energy, which depends on the relative atom numbers. We attribute this to an interaction-induced increase of the lattice depth due to the self-trapping of the atoms.

A general method for synthesis of GPI anchors illustrated by the total synthesis of the low-molecular-weight antigen from Toxoplasma gondii

Building blocks: a new, general synthetic strategy, which allows the construction of branched glycosylphosphatidylinositols (GPIs), enables the synthesis of parasitic glycolipid 1 from Toxoplasma gondii. In addition, the structure is further confirmed by recognition of monoclonal antibodies.

[Cardiac resynchronization therapy for heart failure - from experimental pacing to evidence-based therapy]

Within the last decade, cardiac resynchronization therapy (CRT) has become an evidence-based cornerstone for a subset of patients with chronic heart failure. For those, who suffer from ischemic or non-ischemic cardiomyopathies at NYHA III or IV, have sinus rhythm, a left bundle branch block and a left ventricular ejection fraction below 35%, CRT has evolved as an important treatment option with promising results. Numerous studies have shown that in these patients pacemaker-mediated correction of intra- and interventicular conduction disturbances can improve not only clinical symptoms, exercise tolerance and the frequency of hospitalizations, but even more important the overall mortality. These clinical results are due to several functional aspects. In the failing heart characteristic intra- and interventricular alterations in electrical conduction result in mechanical asynchrony that leads to an abnormal contraction of the left ventricle with delayed activation of the lateral wall, a paradoxical septal movement, a reduced diastolic filling and a mitral regurgitation due to dyssynchrony of papillary muscle activation. It is conceivable that these functional changes have fatal consequences for the failing heart. AV-optimized left- or biventricular stimulation by modern pacemakers can correct the pathological dyssynchrony, thereby improving cardiac function and clinical outcome in these patients. Although tremendous progress in cardiac resynchronization therapy has been made during the last decade, a couple of questions still need to be resolved. Critical issues are the identification of patients, who will predictably benefit from CRT, the value of CRT-pacemakers versus CRT-ICDs, and the usefullness of CRT in patients with atrial fibrillation.

Septic arthritis of the knee after anterior cruciate ligament surgery: a stage-adapted treatment regimen

BACKGROUND

Septic arthritis is a rare complication after anterior cruciate ligament surgery. All case series reported so far have been retrospective, and case numbers of septic arthritis have ranged from 4 to 11.

HYPOTHESIS

A stage-adapted treatment regimen for septic arthritis after anterior cruciate ligament surgery can provide reliable results.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

From June 1993 to May 2003, 24 patients met the inclusion criteria for this study. The average age at trauma was 32.5 years. Treatment protocol was based on the grade of infection. Options included transarthroscopic treatment for Gaechter grades 1 and 2 infections or medial and lateral arthrotomy for grades 3 and 4 infections. Graft retention was decided based on clinical findings. The setting was a specialized trauma hospital. Follow-up included International Knee Documentation Committee forms, radiographs, and the Tegner and Lysholm scores at a mean of 66 months (range, 11-142) after treatment.

RESULTS

In all cases, treatment of infection was successful; overall, a mean of 2.2 operations were required. In 7 cases, it was possible to salvage the graft. The Tegner activity level before the knee injury was 6.1 points. At follow-up, the average score was 3.8 points. The postoperative subjective International Knee Documentation Committee score averaged 64. The mean Lysholm score was 65.6. On clinical examination, a mean extension deficit of 3 degrees and a mean maximum flexion of 120 degrees were found. In the single-legged hop test, a mean capacity of 63% compared with the uninjured side was measured.

CONCLUSION

The described treatment regimen gives reliable results for this complication. There were no recurrences of septic arthritis or bone infection. Early infection can be managed arthroscopically with satisfactory results regarding the treatment of infection. In advanced or chronic infection, a more radical approach seems favorable. Results in these cases are overall only fair compared with patients with an uncomplicated anterior cruciate ligament reconstruction.

Immunohistochemical investigation with carbohydrate monoclonal antibodies in cystic fibrosis

BACKGROUND

Cystic fibrosis is one of the most common inherited diseases in Europe. In patients with cystic fibrosis, the serum levels of the tumour marker antigens CA19-9 and CA50, which are normally found in the epithelium of many organs, are increased. No such finding has been reported for CA242, another ubiquitous tumour marker antigen. We set out to investigate immunohistochemically the correlation of CA19-9 and CA50 with cystic fibrosis and to compare the effect of antibodies against these three tumour markers with regard to improved immunohistochemical results.

MATERIALS AND METHODS

Paraffin-embedded tissue from different organs of 18 patients with cystic fibrosis was studied. Immunohistochemical reactions were performed with antibodies against CA19-9, CA50 and CA242 followed by visualisation with the ABC method.

RESULTS

Immunohistochemical reactions in different tissues were uniform. Anti-CA19-9 reacted less intensive than anti-CA50 and anti-CA242. The antibodies generally bound to cell membranes and compounds of the cytoplasm.

CONCLUSIONS

This study demonstrates immunohistochemically the epitopes of monoclonal carbohydrate antigens (CA-19-9, CA-50 and CA 242) in cystic fibrosis for the first time. We also supposed that cystic fibrosis patients show increased serum levels of CA242. However, none of the three antibodies investigated seems suitable for the immunohistochemical diagnosis of cystic fibrosis.

Selective downregulation of rat cardiac beta 1-adrenoceptors by cyclosporine A: prevention by diltiazem or angiotensin-converting enzyme inhibitors

OBJECTIVES

This study attempted to determine whether long-term treatment with cyclosporine A in rats affects cardiac beta 1-adrenoceptors and whether this can be prevented by angiotensin-converting enzyme inhibitors or calcium-entry blocking agents.

BACKGROUND

In the transplanted human heart the density of beta 1-adrenoceptors decreases with time after transplantation, whereas that of beta 2-adrenoceptors does not. Because heart transplant recipients are treated with cyclosporine A, we studied whether administration of cyclosporine A in rats might cause this beta 1-adrenoceptor downregulation.

METHODS

We performed two studies. First, we treated groups of 10 male normotensive Wistar rats orally with 30 mg/kg body weight per day of cyclosporine A, 10 mg/kg per day of enalapril and 60 mg/kg per day of diltiazem, alone or in combination, for 6 weeks each. Second, we treated groups of 15 male normotensive Wistar rats orally with 15 mg/kg per day of cyclosporine A and 10 mg/kg per day of lisinopril, alone or in combination, for 6 weeks each. At the end of each treatment regimen, cardiac beta-adrenoceptor density and subtype distribution were assessed by (-)-[125I]iodocyanopindolol binding.

RESULTS

Both doses of cyclosporine A caused a significant decrease in cardiac beta 1-adrenoceptor density without affecting beta 2-adrenoceptor density. Although diltiazem and the angiotensin-converting enzyme inhibitors alone did not affect cardiac beta-adrenoceptors, they prevented the cyclosporine A-induced downregulation of beta 1-adrenoceptors.

CONCLUSIONS

In normotensive Wistar rats, cyclosporine A causes a significant decrease in cardiac beta 1-adrenoceptors without affecting beta 2-adrenoceptors. This can be prevented by diltiazem or angiotensin-converting enzyme inhibitors. In heart transplant recipients, who undergo long-term treatment with cyclosporine A, there is a very similar beta 1-adrenoceptor down-regulation with time after transplantation. Thus, administration of cyclosporine A may cause these beta-adrenoceptor subtype alterations.

Preventive effects of diltiazem on cyclosporin A-induced vascular smooth muscle dysfunction

Cyclosporin A may cause vascular smooth muscle dysfunction due to calcium overload as a consequence of chronically augmented calcium influx. In the present study, the responsiveness to vasocontrictors was investigated in rats after chronic treatment for 6 weeks with placebo, cyclosporin A (30 mg/kg per day), diltiazem (60 mg/kg per day), or cyclosporin A plus diltiazem. Twenty-four hours after the last oral treatment the animals were sacrificed and rings of the thoracic aorta were suspended in organ chambers under isometric conditions in the absence of cyclosporin A or diltiazem. Chronic treatment with cyclosporin A significantly augmented contractions to angiotensin II (10(-9)-10(-5) M). This effect was prevented by cotreatment with diltiazem. Diltiazem did not affect the cyclosporin A-induced reduction in the response to potassium chloride (10-80 mM). The contractions to phenylephrine (10(-9)-10(-6) M) and endothelin-1 (10(-9)-10(-7) M) were not significantly different in the four groups. The preventive effect of diltiazem against the cyclosporin A-induced hypersensitivity to angiotensin II supports the hypothesis of increased calcium influx during cyclosporin A therapy. The results may provide an additional rationale for the use of calcium antagonists in the treatment of the vascular side effects of cyclosporin A.

Calcium entry blockade may prevent cyclosporin A-induced hypersensitivity to angiotensin II and endothelial dysfunction in the rat aorta

Vascular smooth muscle dysfunction after chronic treatment with cyclosporin A was in part explained by chronically augmented calcium influx leading to calcium overload. The potential protective effect of calcium antagonism with diltiazem as regards endothelial and vascular smooth muscle reactivity was investigated during chronic treatment with cyclosporin A. Male Wistar rats were orally treated for 6 weeks with either cyclosporin A (30 mg.kg-1 x day-1 in 1 ml, n = 8), with the vehicle alone (n = 10), with diltiazem (60 mg.kg-1 x day-1, n = 10) or with a combination of cyclosporin A and diltiazem (30 mg.kg-1 x day-1 and 60 mg.kg-1 x day-1, n = 8), respectively. Rings of the isolated thoracic aorta were mounted in organ chambers to measure isometric force. Chronic treatment with diltiazem alone did not affect the responsiveness to any of the drugs tested, but the augmentation of contractions to angiotensin II (10(-9) to 10(-6) M) after treatment with cyclosporin, was prevented by co-treatment with diltiazem. Co-treatment with diltiazem, however, did not affect the response to potassium chloride (20-80 mM), endothelin-1 (10(-9) to 10(-7) M) or phenylephrine (10(-9) to 10(-6) M). Endothelium-dependent relaxations to calcitonin gene-related peptide (CGRP, 10(-10) to 10(-7) M) and acetylcholine (10(-8) to 10(-5) M) were reduced in cyclosporin A treated rats. Co-treatment with diltiazem normalized the response to CGRP. The response to acetylcholine was not significantly affected.(ABSTRACT TRUNCATED AT 250 WORDS)

Endothelial and vascular smooth muscle function after chronic treatment with cyclosporin A

We wished to characterize the altered reactivity of vascular smooth muscle and endothelial cells in rat aorta during chronic treatment with cyclosporin. Male adult rats were treated orally for 6 weeks with either cyclosporin A (30 mg/kg/day in 1 ml olive oil, n = 9) or with vehicle alone (n = 10). Rings of isolated thoracic aorta were mounted in organ chambers to measure the change in isometric force in response to smooth muscle-contracting drugs and endothelium-dependent and independent vasodilators. Contractions to potassium chloride (20-80 mM) were markedly reduced in cyclosporin-treated rats. Contractions to phenylephrine (10(-10)-10(-6) M) were reduced at high concentrations (> or = 10(-7) M); those to endothelin-1 (10(-10)-10(-7) M) were not significantly altered. In contrast, contractions to angiotensin II (AII 10(-9)-10(-6) M) were significantly augmented. Endothelium-dependent relaxations to acetylcholine (ACh 10(-8)-10(-5) M) or ADP (10(-7)-10(-5) M) were reduced in cyclosporin-treated rats; endothelium-independent relaxations to SIN-1 (10(-7)-10(-5) M) and atrial natriuretic peptide (ANP 10(-10)-10(-7) M) remained unaffected. Thus, chronic treatment with cyclosporin affects both endothelium-dependent vasodilation and vascular smooth muscle contraction in rat aorta depending on the stimulus applied. The enhanced response to AII and the reduced release of endothelium-derived relaxing factor (EDRF) may contribute to augmented vascular tone and further damage to the arterial wall.

[Prenatal diagnosis and obstetric management of a case of Klippel-Trenaunay-Weber syndrome]

A description is given of a case of Klippel-Trenaunay-Weber syndrome diagnosed by sonography in the 28th week of pregnancy. The ultrasound findings established in the course of pregnancy are presented. Whereas minor variants of this syndrome normally do not represent a birth hindrance, a cesarean section was indicated in the present case on the basis of the size of the deformation--especially at the hip--an in order to save the child.

Anti-oestrogenic effects of tamoxifen on mammary gland and hypophysis in female rats

Adult ovariectomized rats were treated for 14 days with oestradiol benzoate (E2B) 15 micrograms/kg/d and oestradiol benzoate 15 micrograms/kg/d + progesterone (PRO) 15 mg/kg/d for induction of mammary gland parenchymal stimulation. Histological examination and whole mount preparation demonstrated that ductal growth in the mammary gland after E2B treatment was completely antagonized by tamoxifen (TAM) 0.5 mg/kg/d. Parallel DNA concentrations in the mammary gland were decreased to control levels by TAM 0.5, 5 and 15 mg/kg/d. E2B-induced hyperprolactinaemia in the forenoon (basal secretion was equally reduced by TAM 0.5, 5 and 15 mg/kg/d). In the afternoon, when prolactin (Prl) secretion is at its maximum, TAM 0.5 mg/kg/d turned out to be ineffective to abolish Prl surge, but TAM 5 and 15 mg/kg/d reduced serum Prl concentrations in a dose-related manner. Immunoperoxidase staining of Prl cells in the pars distalis of the hypophysis indicated that adaptive hypertrophy and signs of hypersecretion after E2B were abolished by TAM 5 mg/kg/d. Luteotrophic cells clearly showed cellular atrophy, regression and secretory inactivity. Maximal tubulo-alveolar mammary parenchymal stimulation in rats treated with E2B-PRO was slightly inhibited by TAM 0.5 mg/kg/d. Histology showed a small disseminated parenchymal islet. DNA concentrations only were partially decreased by the anti-oestrogen though serum Prl concentrations were found to be completely decreased to control levels. Secretory activity of Prl cells was reduced by TAM 0.5 mg/kg/d. In E2B-PRO treated rats lisuride had poor inhibitory activity on Prl levels and none on DNA concentrations in the mammary gland. Combined treatment with TAM and lisuride significantly decreased DNA concentration in the mammary gland compared to animals which received E2B-PRO. Also Prl levels were at a minimum. Histology performed on the mammary gland showed only slight tubulo- but no tubulo-alveolar activation. Luteotrophic cells in the pituitary gland stained by the immunoperoxidase technique appeared regressive, shrunken and atrophied.