Local terrestrial snails as natural intermediate hosts of the zoonotic parasite Angiostrongylus cantonensis in the new European endemic area of Valencia, Spain

AIM

The rat lungworm, Angiostrongylus cantonensis, has recently been found in the city of Valencia, parasitizing rats, Rattus norvegicus and Rattus rattus, its natural definitive hosts. This is the first finding of this zoonotic nematode in continental Europe. After informing local and national health authorities, the collection of local terrestrial snails took place with the aim of elucidating their potential role as intermediate hosts of A. cantonensis.

METHODS AND RESULTS

A total of 145 terrestrial snails, belonging to the species Cernuella virgata, Cornu aspersum, Eobania vermiculata, Otala punctata, Pseudotachea splendida, Rumina decollata and Theba pisana, were randomly collected between May and December 2022 in public gardens, parks and orchards in six districts of Valencia, in five of which A. cantonensis had been reported previously in rats. Once collected and identified, the snails were frozen at -20°C. Subsequently, the DNA was isolated and screened by PCR using specific primers targeting the A. cantonensis COI gene. Seven individual snails, belonging to the species C. virgata, C. aspersum and T. pisana, were positive, for an overall prevalence of 4.8%. The PCR product from one of them was sequenced by Sanger sequencing.

CONCLUSIONS

The three positive terrestrial snail species are among the edible species that are frequently included in various dishes in Spain. C. virgata is reported as a previously unrecorded intermediate host and should be added to the list of more than 200 species of terrestrial snails that have been reported worldwide as intermediate hosts of the rat lungworm. Considering that these terrestrial snails may release infective larvae of A. cantonensis on leafy green vegetables on which they feed and during their handling and preparation for consumption, prophylactic measures to prevent human neuroangiostrongyliasis in Valencia and other regions to which this zoonotic parasite may spread are recommended.

Keratoplastiken im Kindes- und Jugendalter

Hintergrund Die Voraussetzungen für das langfristige Überleben einer perforierenden Keratoplastik sind im Säuglings- und Kindesalter aufgrund immunologischer Besonderheiten, der eingeschränkten Untersuchbarkeit sowie reduzierter Compliance und Therapieadhärenz à priori ungünstig. Jedoch stellt eine Hornhautübertragung oftmals die einzige Möglichkeit zur Prävention einer Amblyopie dar und ist somit alternativlos. Wir untersuchten das Indikationsspektrum, das Transplantatüberleben und das Komplikationsspektrum in einem bizentrischen Register aller Keratoplastiken im Kindesalter.

Material und Methoden Aus den elektronischen Transplantatregistern der beiden Zentren wurden alle Patienten recherchiert, die zum Zeitpunkt der jeweils 1. Keratoplastik das 18. Lebensjahr noch nicht vollendet hatten. Aus den Krankenakten wurden die Indikation, etwaiges Transplantatversagen, die Sehschärfe, Verlust des Augapfels und weitere Komplikationen systematisch recherchiert.

Ergebnisse Es wurden insgesamt 104 Augen von 95 Patienten (54 % weiblich) identifiziert. Das Durchschnittsalter bei der Operation betrug im Median 14 Jahre (Quartile 8 und 16 Jahre). Die Nachbeobachtungszeit lag im Median bei 2,7 Jahren. Es zeigten sich folgende Indikationen: Keratokonus (39 %), perforierende Verletzung (18 %), nicht herpetische Hornhautnarben (12 %), herpetische Hornhautnarben (6 %), Sklerokornea (3 %), Verätzung (3 %) und die heterogene Gruppe der sonstigen Indikationen (19 %). Das nach Kaplan-Meier geschätzte klare Transplantatüberleben reichte zum Zeitpunkt der Durchschnittsnachbeobachtungszeit von 100 % (Keratokonus) bis 35 % (Sklerokornea). Ein Verlust des Augapfels war ausschließlich nach perforierender Verletzung (n = 2) zu verzeichnen. Nach 1 Jahr sind in der Kaplan-Meier-Schätzung alle Transplantate in der Gruppe der Säuglinge eingetrübt. In der Gruppe der Kleinkinder bis Jugendlichen sind 90 % der Transplantate zu diesem Zeitpunkt noch klar.

Schlussfolgerungen Die Prognose der Keratoplastik im Kindesalter hängt sowohl von der initialen Indikation und damit indirekt von der Grunderkrankung als auch vom Alter ab. Eine besonders schlechte Prognose zeigte die Gruppe der Säuglinge mit einem nur sehr kurzen Transplantatüberleben. Bei den Indikationen zeigte die Gruppe der Kinder mit Keratokonus die besten Ergebnisse. Als prognostisch ungünstig erwiesen sich Sklerokornea sowie perforierende Augenverletzungen.

Polarity of GaN

Convergent beam electron diffraction (CBED) was applied to study polarity of GaN heterolayers grown by MOCVD on sapphire and SiC substrates and also mechano-chemically polished bulk GaN platelet crystals grown from Ga melt under hydrostatic pressure of N. Heterolayers of GaN grown on both types of substrates showed (0001) Ga polarity, e.g. Ga to N along c-axis. Mechano-chemical etching of bulk GaN platelet crystals leaves one surface smooth and the opposite surface rough with visible damage caused by mechanical polishing. CBED studies showed that the smooth surface has (0001) N polarity, confirming our earlier studies.

[Pustules from the cow barn]

A 54-year-old cattle farmer presented with crusty purulent plaques in the neck area. The clinical picture and microscopical proof of hyphae in the skin smear combined with Wood's lamp testing led to the diagnosis of Tinea barbae, a mycological infection of the skin transmitted by cattle (typically Trichophyton verrucosum). Therapy with itraconazole 200 mg q.d. p.o. and miconazole ointment 1×/day over 2 weeks was successful. This case report and its image are designed to bring attention to this rarely diagnosed pathology.

Approaching the evolutionary advantage of ancillary types of haemoglobin in Daphnia magna by simulation of oxygen supply

The planktonic crustacean Daphnia magna synthesizes haemoglobin (Hb) macromolecules of variant subunit composition and oxygen affinity. This is one of the strategies by which the animals cope with variations in environmental conditions such as ambient oxygen tension. The enrichment of high-affinity Hb molecules in the haemolymph of hypoxia-exposed animals is thought to reduce Hb synthesis costs due to an enhanced transport efficiency of these molecules in comparison to the low-affinity Hb molecules. How great this economic advantage is, and under which conditions this benefit disappears, is still not fully understood. Here we implemented a rigorously simplified model of the daphnid body and described the transport of oxygen from the environment via the haemolymph to the tissues in terms of the convection–diffusion–reaction equation. The model was validated by comparing various model predictions with experimental data. A sensitivity analysis was used to evaluate the influence of parameter uncertainties on the model predictions. Cost–benefit analysis revealed in which way at the system's level the increase in Hb oxygen affinity improves the oxygen loading at the respiratory surfaces and impairs the release of oxygen to the tissues. The benefit arising from the improved oxygen loading exceeds the disadvantage of impaired unloading only under conditions where the ambient oxygen tension is critically low and the Hb concentration is high. The low-affinity Hb, on the other hand, provides an advantage given that the Hb concentration is low and the ambient oxygen tension is well above the critical level. Computer-aided modelling and simulation therefore provide valuable mechanistic insights into the driving forces that could have shaped the evolution of globin genes in daphnids.

ENZIAN-Score, eine Klassifikation der tief infiltrierenden Endometriose

The ENZIAN-Score is presented as a new instrument to classify the deep infiltrating endometriosis. Especially the retroperitoneal part of the severe endometriosis is focussed on. In analogy to an oncological staging four different stages are pronounced. The localisation and the expansion of the endometriosis nodule was indicated to different subgroups. The still used rAFS-score is of no clinical evidence, as we pointed out in a retrospective study of our patients with severe intestinal endometriosis.

Mayer-von Rokitansky-Kuster-Hauser syndrome in association with a hitherto undescribed variant of the Holt-Oram syndrome with an aorto-pulmonary window

We report on the association of Mayer-von Rokitansky-Küster-Hauser syndrome (MRKHS) with a unique form of Holt-Oram syndrome (HOS) with an aorto-pulmonary window. A 24-year-old Turkish woman was referred to our hospital because of primary amenorrhoea. Both her vagina and uterus were absent, and the diagnosis of MRKHS was established. Laparoscopic creation of a neovagina by the modified Vecchietti technique was performed. A rare congenital malformation of the heart, namely an aorto-pulmonary window, had required cardiac surgery when the patient was a 6-month-old infant. This cardiac malformation plus associated upper limb anomalies led to the clinical diagnosis of HOS. To the best of our knowledge, this is only the second report in the scientific literature on the concurrence of MRKHS and HOS, and the first published case of HOS with an aorto-pulmonary window as the cardiac malformation.

Simplified microvascular suture techniques for rat liver transplantation as a microsurgical model with arterial blood supply

The methods for liver transplantation in the rat mainly used do not include reconstruction of the arterial blood supply to the liver. Furthermore, to ensure a short anhepatic phase these methods almost all entail specially developed cuff anastomoses in the recipient operation instead of the conventional microvascular suture technique. Thus an acceptable survival rate can be attained in the experimental animals. This detailed description of simplified microvascular suture techniques is intended to present an alternative to the cuff anastomoses used almost exclusively. In the donor operation with this method, the liver is dissected with an arterial pedicle including the abdominal segment of the aorta, and the liver is flushed in situ not only via the portal vein, but also via the hepatic artery. The organ is implanted in the recipient animal using simplified microvascular suture reconstruction of the arterial blood supply to the liver. Use of telescopic spectacles with 2-fold magnification has proven to be adequate for the entire procedure. With mastery of this method of rat liver transplantation, the average duration of the anhepatic phase is about 20 min, substantially below the 30-min limit which is critical for the survival of the experimental animals. The donor operation requires about 60 min, and the recipient operation 70 to 80 min. With this method, the spectrum of investigations on liver transplantation which are possible in the rat is substantially extended in that clinical conditions can be reproduced very much more exactly by combination of portal and arterial in-situ flushing in the donor operation and rearterialization of the transplant in the recipient operation, as compared to the transplanted rat liver being supplied only with portal venous blood.

Terminal ileitis with sealed perforation?a rare complication of intestinal endometriosis: case report and short review of the literature

INTRODUCTION

Perforation is a rare complication of intestinal endometriosis. We report on a 38-year-old patient with previously known rectovaginal and ileocecal endometriosis who was referred with an acute abdomen.

CASE REPORT

On abdominal plain film an ileus of small intestine was diagnosed. The patient had fever, and the C-reactive protein was markedly increased. Upon emergency laparotomy an acute terminal ileitis with omentum-sealed perforation and a stenosis of the anterior wall of the rectum due to endometriosis were found. Partial resection of the ileum with end-to-end anastomosis, appendectomy, and short segmental rectum resection were performed. The postoperative course was uneventful. Histological examination corroborated the intraoperative diagnosis of fistulas, perforation and deep ulceration of the intestine consistent with transmural endometriosis.

DISCUSSION

For proper care of these patients excellent cooperation between gynecologists and general surgeons is desirable. A short review of the literature concerning intestinal endometriosis is given.

Easy and effective--web-based information systems designed and maintained by physicians: experience with two gynecological projects

It is well established that medical information sources develop continuously from printed media to digital online sources. To demonstrate effectiveness and feasibility of decentralized performed web-based information sources for health professionals, two projects are described. The information platform of the German Working Group for Information Technologies in Gynecology and Obstetrics (AIG) and the information source concerning the German Registry for in vitro fertilization (DIR) were implemented using ordinary software and standard computer equipment. Only minimal resources and training were necessary to perform safe and reliable web-based information sources with a high correlation of effectiveness in costs and time exposure.

Endometriose und Malignom

Malignant tumors arising from endometriosis are rare. A frequency of about 1% has been reported with in 80% the ovary, and in 20% extragonadal sites being affected. The most common extragonadal manifestations are the rectosigmoid and the rectovaginal septum. For extragonadal malignant tumors arising from endometriosis, complete resection followed by post-operative radiotherapy, possibly plus adjuvant progestin therapy, is the treatment of choice. Endometriosis-associated ovarian carcinomas are likely to present with lower stage disease and predominantly lower grade tumors. While their treatment follows that of common ovarian cancer, a poorer response to chemotherapy must be considered. As unopposed estrogen replacement therapy has been identified as a risk factor for the development of endometriosis-associated cancer, it is not recommended for hormone replacement therapy in women with a history of endometriosis. Loss of heterozygosity and mutations of the PTEN tumor suppressor gene may be early events of tumorigenesis. Endometriosis and its malignant transformation, perhaps, may serve as a suitable model in this regard. According to recent studies, endometriosis is associated with an increased relative risk of non-Hodgkin lymphoma.

Die aktuellen IT-Systeme in der gynäkologischen Onkologie

Information technology has been integrated in gynecological oncology treatment. Therefore, new software has been established in hospitals and out-patient clinics. A German law concerning data collection in oncology has attempted to unify different strategies. All intentions to establish new documentation systems for tumor diseases need a standardized basic data set. Nevertheless, local governmental health organizations are not yet prepared to implement a global information system such as prenatal and perinatal care databases. Financial support and political work is therefore needed.

Photoradiation of perfused placental tissue--a suitable in vitro model for photodynamic therapy?

Our aim was to evaluate the isolated placental lobule as a model to study the cytotoxic effects of photodynamic therapy (PDT) in vitro. Ten human placental lobules were dually perfused with a modified medium 199 for a 4-hour period. Photosan III was added to the fetal perfusate at a dose of 5 mg/kg tissue, and laser light (630 nm wavelength) provided by an argon-pumped dye laser was applied at 50 J/cm2 in the experimental group (n=5). Potassium and lactate dehydrogenase (LDH) release into the perfusate as well as the transplacental creatinine passage from PDT-treated placentas and control placentas (n=5) were compared, and light microscopic examinations of the placental tissue were performed after the experiments. Potassium release into the fetal perfusate was higher in the PDT-treated placental lobules (p<0.05), and weight gain during the artificial perfusion suggests the development of edema only in the photoradiated lobules (p<0.01). The release of the bigger molecules of the LDH however was comparable in the two experimental groups, and transplacental creatinine passage was not affected by photoradiation. Light microscopic examinations demonstrated lesions at the cytotrophoblast, the syncytiotrophoblast and the endothelium of the fetal vessels of the photoradiated placentas, although they were not specific and could also be found in the control tissue. We conclude that the isolated placenta may be used to study cytotoxic effects of photoradiation in vitro, but better specifity and sensitivity might be achieved if a. The perfusion time is prolonged to make the difference between the experimental and the control group clearer and b. Electron microscopic investigations are made to demonstrate intracellular lesions of the mitochondria and the endoplasmic reticulum.

[Fetomaternal macrotransfusion after attempted external version]

BACKGROUND

External cephalic version is an alternative to both vaginal breech delivery and to caesarean section. The objective of this study was to summarize potential complications of external cephalic version. Which means are available for early detection and treatment of these complications?

CASE REPORT

A 28-year-old 1/0 with breech presentation was considered for external cephalic version at the 38th week of gestation. As three version attempts failed, the patient was discharged after normal fetal heart tone (FHT) registration and normal ultrasonographic findings on the next day. Caesarean section was planned six days later. On the day of admission, FHT registration revealed a decreased beat-to-beat variability and a sinusoidal baseline. Doppler-flow indices of the A. umbilicalis and A. cerebri media were normal, although middle cerebral artery peak systolic velocity was increased. Rapid caesarean section was performed, and an anemic baby (hemoglobin 3.4 g/dl) was born. After transfusion of 100 ml red blood cells, further development of the newborn was normal.

DISCUSSION AND CONCLUSION

Fetomaternal macrotransfusion may be a rare complication of external cephalic version, occurring even several days after the mechanical manipulation. FHT registrations and ultrasonographic doppler flow measurements performed periodically unit birth are necessary to detect such complications early. The Kleihauer-Betke test is the method of choice to diagnose fetomaternal macrotransfusion.

[Concepts of quality assurance in obstetrics and gynecology]

The safeguarding of quality has reached an essential position in medical area. The creation of corresponding concepts with definition of tasks for quality assessment is one of the most important challenges for public health organizations and politicians. The still established projects in gynecology and obstetrics in Germany now carried out that the conscience for the necessity of quality safeguarding is in high gear.A summary of the quality safeguarding projects and tools is given.

[Publishing guidelines on the internet]

Guidelines are well established in modern medicine as a tool of quality assurance. New developments in Information Technology (IT) alters strategies in communication, and influences the publication of important notes or research findings. Acceptance and efficiency of guidelines depends on promptness of publication. Using the internet to publish guidelines does not only improve success of transferal but also changes interaction between physicians and patients.

Diabetes mellitus and islet cell specific autoimmunity as adverse effects of immunsuppressive therapy by FK506/tacrolimus

The induction of diabetes has been recognised as adverse effect of the immunsuppressive drug FK506/Tacrolimus. The aim of this study was to clarify whether insulinopenia or insulin resistance dominates and whether islet cell autoantibodies are present in patients treated by FK506. We investigated 58 patients 1-3 years after liver transplantation while under therapy with FK506 or CsA and prednisolone (0-7.5 mg) for basal blood glucose levels and islet-cell specific autoantibodies. A subgroup of 20 patients on FK506, 10 patients on cyclosporin and 15 healthy volunteers were metabolically tested by oGTT. Five patients had diabetes pre-transplantation. After transplantation, 9/28 FK506-treated patients developed newly diagnosed diabetes compared to 0/25 cyclosporin-treated patients (p<0.01). Both patient groups showed significantly higher fasting blood glucose, insulin or C-peptide levels compared to controls. Through the oGTT, FK506-treated patients without diabetes, but not cyclosporin-treated patients, had higher C-peptide levels compared to controls (p<0.05). Five/32 patients on FK506 compared to 0/26 patients on cyclosporin (p<0.05) had islet cell specific autoantibodies, mainly ICA without GAD- or IA2-Ab, a feature described for latent autoimmune diabetes in adults. ICA positivity was correlated to the diabetes associated HLA haplotype DR4/DQ*0302 (p<0.05). Although the interpretation of our metabolic data in patients with concomitant liver disease and prednisolone therapy has limitations, we suggest insulin resistance caused by treatment with FK506. However, manifestation of diabetes was associated with relative insulinopenia rather than insulin resistance in patients on FK506. Immunsuppressive therapy by FK506 was not able to suppress islet cell autoimmunity, and may even induce it in genetically predisposed patients.

Digoxin, flecainide, and amiodarone transfer across the placenta and the effects of an elevated umbilical venous pressure on the transfer rate

Clinical observations suggest that flecainide might pass the placenta more easily than digoxin, and that its transfer is less disturbed in case of hydrops fetalis than that of digoxin. The purpose of the study was to compare the materno-fetal transplacental transfer of digoxin, flecainide, and amiodarone, another antiarrhythmic agent used in the treatment of fetal tachyarrhythmia, and to assess the effect of an elevated umbilical venous pressure (UVP) on the transfer rate. Isolated lobules of 16 human placentas were dually perfused after spontaneous delivery or caesarean section. The transplacental transfer (area under the curve in the maternal compartment [maternal AUC], area under the curve in the fetal compartment [fetal AUC], kinetic parameters) of digoxin, flecainide, and amiodarone was calculated after these drugs were added to the maternal circuit. In five experiments, the effect of increased UVP on the transplacental transfer rate was assessed by elevating the UVP by 10 cm H2O. Flecainide efflux out of the maternal compartment was significantly greater than that of digoxin (maternal AUC 57.4% +/- 5.1 %/min vs 73.9% +/- 1.5%/min), whereas the flecainide influx into the fetal circulation was smaller (fetal AUC 9.3% +/- 4.1%/min vs 11.5% +/- 2.0%/min). Only in 50% of the experiments were the smallest amounts of amiodarone detectable in the fetal compartment. An elevation of the UVP reduced the influx of digoxin and flecainide into the fetal compartment (fetal AUC) from 11.5% +/- 2.0%/min to 7.4% +/- 1.9%/min and from 9.3% +/- 4.1% to 4.7% +/- 1.4%/min, respectively. Materno-fetal transplacental transfer of digoxin, flecainide, and amiodarone decreases in this sequence. Fetal cardiac insufficiency accompanied by an elevation of the UVP might reduce the transplacental transfer of these drugs, although no significant difference could be found between the reduction of transfer of digoxin and flecainide.

Extracorporeal perfusion of the human uterus as an experimental model in gynaecology and reproductive medicine

Experimental perfusion of various organs has primarily been used in transplantation medicine to study the physiology, pathophysiology and metabolism of tissues and cells. The purpose of this study was to establish an experimental model for the extracorporeal perfusion of the human uterus with recirculation of a modified, oxygenated Krebs-Henselait solution, in comparison with a non-recirculating perfusion system. With consent of the patients we obtained 25 uteri after standard hysterectomy. We performed an isovolumetric exchange of the perfusion medium at different intervals from 1 to 6 h and examined pH, pO(2), pCO(2), lactate, lactate dehydrogenase and creatine kinase by taking arterial and venous samples every hour for 24 h. We found the perfusions to be adequate when maintaining flow rates at 15-35 ml/min and at pressures ranging from 70 to 130 mmHg. Isovolumetric exchange of the perfusate every 3-4 h was the maximum interval to keep pH, the arterio-venous gradients of pO(2) and pCO(2), and the other biochemical parameters in physiological ranges. Examination by light and electron microscopy showed well-preserved features of myometrial and endometrial tissue. However, a 6 h exchanging interval led to increasing hypoxic and cytolytic parameters during the whole perfusion period. X-ray studies using digital subtraction angiography and perfusion studies with methylene blue demonstrated the homogeneous distribution of the perfusion fluid throughout the entire organ.

Simulation of herbicide degradation in different soils by use of Pedo-transfer functions (PTF) and non-linear kinetics

The degradation behaviour of bentazone in 14 different soils was examined at constant temperature and moisture conditions. Two soils were examined at different temperatures. On the basis of these data the influence of soil properties and temperature on degradation was assessed and modelled. Pedo-transfer functions (PTF) in combination with a linear and a non-linear model were found suitable to describe the bentazone degradation in the laboratory as related to soil properties. The linear PTF can be combined with a rate related to the temperature to account for both soil property and temperature influence at the same time.

[TNF-alpha secretion by peritoneal macrophages in endometriosis]

Beside of other cytokines and growth-factors Tumor Necrosis Factor Alpha (TNF-alpha) exerts as a macrophage-derived cytotoxic product a variety of immunologic effects in the human organism. It is also an important angiogenetic factor and regarding its cytotoxicity toward gametes TNF-alpha plays an essential role as pelvine mediator of sterility. The purpose of our study was to evaluate the TNF-alpha-synthesis of Peritoneal-Macrophages (PM) in patients with and without endometriosis and to determine if a correlation exists between TNF-alpha-synthesis and various degrees of the activity of endometriosis. For reasons of sterility 40 women underwent diagnostic laparoscopy and were staged according to the rAFS-classification as well as the macroscopic aspect of activity into a control group with endometriosis-free pelvic situs (n = 14) and three subgroups characterized by the increasing stage of the disease (n = 26). The TNF-alpha-concentrations (median) in the control group were 3.3 pg/ml, in group 2 with stage I/II rAFS and only low active endometriosis 60.2 pg/ml, in group 3 with stage I/II rAFS but high active endometriosis 83.2 pg/ml and in group 3 with stage III/IV rAFS 168 pg/ml. These data were statistically high significant and showed good conformity with the histological findings. We found significant higher TNF-alpha-concentrations in the peritoneal fluid of patients with endometriosis than in the peritoneal fluid of healthy women. There is a correlation between TNF-alpha-concentrations and the degree of disease.

[Laparoscopic implantation of catheters for continuous ambulatory peritoneal dialysis]

Continuous ambulatory peritoneal dialysis (CAPD) has become an established procedure and is an equal alternative to haemodialysis (HD) in the management of terminal renal failure. Nevertheless CAPD still plays a minor role compared with HD (10% of all dialyses). CAPD offers advantages in quality of live but is still associated with a significant number of complications. The improvement of surgical technique and development of new peritoneal dialysis catheters (PDK) improved the results of peritoneal dialysis. 3 methods for implantation of PDK are used: the open surgical technique, the blind percutaneous procedure and the laparoscopic method. The latter technique is currently an accepted practice. 10 patients were treated by the laparoscopic method. Additionally to the PDK-tunnel of the abdominal wall we used 2 trocars (1 x 5 mm, 1 x 12 mm). Advantages of this technique are avoiding of perforating lesions, possibility for further operations and a safe implantation of the PDK. Peritoneal dialysis was started 7 days after operation with initially low dialysate volumes. The observed incidence of complications and removed catheters are comparable to the reports in the literature.

[Modification of transplacental digoxin transfer in the isolated placental lobule]

Digoxin is widely used in the transplacental therapy of fetal tachyarrhythmia. Unfortunately, in cases with severe cardiac insufficiency and hydrops fetalis, transplacental passage of digoxin is often hampered and therapy therefore ineffective. The present study was designed to establish the isolated placental lobule to quantify transplacental digoxin passage under different experimental conditions. Ten human placentas were obtained immediately after delivery, and a lobule was dually perfused after cannulating a small artery and vein of the chorionic plate and piercing four catheters through the corresponding basal plate. Flow rates were 12 ml/min in the maternal circuit and 6 (I) respectively 3 ml/min (II) in the fetal circuit. The maternal circuit was spiked with digoxin to 6.18 +/- 0.40 ng/ml, and transplacental passage was calculated from repeated fetal and maternal perfusate samples (Fluorescence-Polarization-Immunoassay; TDx, Abbott Laboratories). Within three hours of recirculating perfusion with a fetal flow rate of 6 ml/min (I), digoxin concentrations in the maternal circuit (400 ml) declined to 3.56 +/- 0.09 ng/ml, whereas digoxin levels in the fetal compartment (200 ml) increased to 2.58 +/- 0.37 ng/ml. With a fetal perfusion rate of 3 ml/min (II), the efflux of digoxin out of the maternal circuit was lower (p < 0.05) and the influx in the total compartment was reduced (fetal digoxin concentrations reached only 26.9 +/- 10.6% vs. 39.1 +/- 5.5% of the initial maternal digoxin concentrations). These data suggest that severe fetal cardiac insufficiency with reduced placental perfusion may be in part responsible for the decrease of transplacental digoxin passage in fetuses with hydrops.

Partitioning of chemically modified low-density lipoprotein in aqueous polymer two-phase systems

Aqueous polyethylene glycol (PEG)-dextran two-phase systems containing 10 mM Tris.HCl (pH 7.4) were used for the partitioning of chemically modified low-density lipoprotein (LDL). Anionic modification connected with an increase in the negative surface charge of lipoproteins favours the accumulation of modified LDL in the top phase. The partition coefficient increases depending on the extent of modification. Cationic modification yields lower values for the partition coefficient. Positively charged LDL favours a bottom-phase accumulation. With weakly charged and nearly neutral particles, the Van der Waals interaction between polymer and particle preponderates over electrostatic interactions, leading to a favoured accumulation of LDL in the PEG-rich top phase. Results of measurements of the relative electrophoretic mobility and the determination of free amino groups are in agreement with the calculated values of the partition coefficient. Because the partitioning of LDL is accompanied by aggregation at the interface, experimental techniques have to be carefully standardized. Subtle differences in the surface properties of modified LDL can be detected.

Future research directions and data requirements for developing ambient ozone guidelines or standards for agroecosystems

The ambient air quality in Central Europe appears to have the potential to adversely affect the productivity of the agroecosystems in that geographic area. Therefore, there is a need to develop, validate, and apply air pollutant exposure-plant response models to explain the relationships between the stochastic chemical climate and ecosystem responses. Such models will have to include numerical terms for the effective air pollutant exposure regime to account for the fluxes of matter, energy and information within the ecosystem and its components. The structure and function of the ecosystem which are influenced by the air pollutant flux can be described by a combination of empirical and mechanistic models. A discussion of such an approach is presented in this paper.

[Residues of active substances after consumption of contaminated food: status report on the evaluation of residues with examples of two drugs]

Pharmacokinetic models are presented for the computation of time courses of blood levels of drugs in man following the consumption of contaminated food. Mathematically, two linear systems of differential equations are set up for the donor organism (e.g., trout) and for the recipient, (e.g., man), where the first system generates the initial conditions for the second. Models of this kind are applied to the transfer of chloramphenicol to man via carp and trout (which had previously been administered this drug) and to the transfer of theophylline to infants via breast milk. Limiting concentration profiles are computed by constructing the most favourable and most adverse combinations of parameters with respect to drug elimination in both the donor and recipient organism.