A reconstitution protocol for the in vitro folded human G protein-coupled Y2 receptor into lipid environment

Although highly resolved crystal structures of G protein-coupled receptors have become available within the last decade, the need for studying these molecules in their natural membrane environment, where the molecules are rather dynamic, has been widely appreciated. Solid-state NMR spectroscopy is an excellent method to study structure and dynamics of membrane proteins in their native lipid environment. We developed a reconstitution protocol for the uniformly (15)N labeled Y(2) receptor into a bicelle-like lipid structure with high yields suitable for NMR studies. Milligram quantities of target protein were expressed in Escherichia coli using an optimized fermentation process in defined medium yielding in over 10mg/L medium of purified Y(2) receptor solubilized in SDS micelles. The structural integrity of the receptor molecules was strongly increased through refolding and subsequent reconstitution into phospholipid membranes. Specific ligand binding to the integrated receptor was determined using radioligand affinity assay. Further, by NMR measurement a dispersion of the (15)N signals comparable to native rhodopsin was shown. The efficiency of the reconstitution could also be inferred from the fact that reasonable (13)C NMR spectra at natural abundance could be acquired.

Prokaryotic expression, in vitro folding, and molecular pharmacological characterization of the neuropeptide Y receptor type 2

G protein-coupled receptors (GPCRs) are a class of membrane proteins that represent a major target for pharmacological developments. However, there is still little knowledge about GPCR structure and dynamics since high-level expression and characterization of active GPCRs in vitro is extremely complicated. Here, we describe the recombinant expression and functional folding of the human Y(2) receptor from inclusion bodies of E. coli cultures. Milligram protein quantities were produced using high density fermentation and isolated in a single step purification with a yield of over 20 mg/L culture. Extensive studies were carried out on in vitro refolding and stabilization of the isolated receptor in detergent solution. The specific binding of the ligand, the 36 residue neuropeptide Y (NPY), to the recombinant Y(2) receptors in micellar form was shown by several radioligand affinity assays. In competition experiments, an IC(50) value in low nanomolar range could be determined. Further, a K(D) value of 1.9 nM was determined from a saturation assay, where NPY was titrated to the recombinant Y(2) receptors.

[Chloroquine/hydroxychloroquine: variability of retinotoxic cumulative doses]

OBJECTIVE

The critical dose of chloroquine/hydroxychloroquine leading to a maculopathy or generalised retinopathy remains undetermined. In the literature, 100 g is considered the dose at which regular vision checks should be performed. Generally, chloroquine is said to be more toxic than hydroxychloroquine. A young patient presenting with toxic maculopathy after 57 g of hydroxychloroquine and a daily dosage of 2 mg/kg body weight prompted us to retrospectively look at our patients examined in this respect over about 1 year.

METHODS

The data of patients who were examined because of chloroquine/hydroxychloroquine intake or a respective maculopathy/retinopathy were retrospectively analysed. The time period was January 2005 until March 2006. Retinal damage was defined by fundus changes and alteration of the multifocal electroretinogram (ERG).

RESULTS

Twenty-one patients--18 women and three men--were examined. The mean age was 51 years (range 6-71). Five of the nine chloroquine-treated patients developed a maculopathy, and one of them developed an additional generalised retinopathy. Of the patients treated by hydroxychloroquine, three of 12 suffered from a maculopathy and one from an additional generalised retinopathy. The cumulative doses leading to retinal damage ranged from 170 g to 1650 g for chloroquine and from 57 g to 1190 g for hydroxychloroquine. The highest cumulative doses without leading to signs of retinopathy were 790 g for chloroquine and 1200 g for hydroxychloroquine.

CONCLUSIONS

There is a high variability of cumulative doses of chloroquine/hydroxychloroquine that lead to a toxic retinopathy. Therefore, early and regular ophthalmologic examinations are recommended. Electrophysiological testing should be performed once a year, corresponding to about 60 g of base with one tablet a day. For electrophysiology, the multifocal ERG has turned out to be the most important test in this regard. However, visual acuity and funduscopy should be performed more frequently.

Silver ion dynamics in silver borate glasses: spectra and multiple-time correlation functions from 109Ag-NMR

The motion of silver ions in (AgI)x-(Ag2O-B2O3)1-x glasses with AgI concentrations of x=0.5 and 0.7 was studied using 109Ag-NMR. The NMR spectra were analyzed in terms of a superposition of two different contributions. These are associated with Ag ions, which hop on vastly different time scales. The existence of dynamic heterogeneity, i.e. the existence of slow and of fast contributions to the hopping dynamics was directly demonstrated using a four-time stimulated-echo experiment. The results are compatible with an intrinsically exponential response. From measurements of the spectra and of two-time correlation functions a Gaussian distribution of energy barriers, hindering the ionic motion, could be mapped out.

Human chorionic gonadotropin and growth factors at the embryonic-endometrial interface control leukemia inhibitory factor (LIF) and interleukin 6 (IL-6) secretion by human endometrial epithelium

BACKGROUND

The elucidation of the molecular mechanisms by which the embryo contributes to its implantation is an area of extensive research. The main objective of this study was to investigate the pattern of leukemia inhibitory factor (LIF) and interleukin-6 (IL-6) secretion by human endometrial epithelium, and their regulation by human chorionic gonadotropin (hCG) and other growth factors present at the embryonic-endometrial interface.

METHODS

Endometrial epithelial cells (EEC) were isolated from biopsies collected at both proliferative and secretory phases of fertile women.

RESULTS

HCG (1-50 IU/ml) increased LIF secretion by EEC cultures derived from follicular phase (up to 285+/-75%) or from secretory phase (up to 212+/-16%). In contrast, hCG reduced IL-6 secretion by EEC in both phases. The hCG/LH receptor gene was transcribed by EEC as evidenced by RT-PCR. Insulin-like growth factors 1 and 2 increased LIF secretion by EEC. Transforming growth factor beta1 stimulated LIF and reduced IL-6 secretion.

CONCLUSIONS

Through hCG, the blastocyst may be involved in the control of its implantation (via an increase of proimplantatory LIF) and tolerance (via an inhibition of proinflammatory IL-6). Other growth factors present at the embryonic-endometrial interface are also involved in the control of LIF and IL-6 endometrial secretion.

Summer variation in the concentration of steroidal sapogenins in and the degree of fungal infection on Narthecium ossifragum plants from Møre og Romsdal County, Norway

Thirty-nine leaf samples of Narthecium ossifragum collected from eight sites in Møre og Romsdal County, Norway, during June-September 1997 and 41 leaf samples collected at five sites in the same county during June-August 1998 were analysed for the concentrations of steroidal sapogenins using GC-MS. The 1998 samples were also examined for fungal elements (conidia and hyphae) after incubation in a moist chamber for 10-14 days. The highest 1997 and 1998 leaf sapogenin concentrations (4881 and 7115 mg/kg dry matter, respectively) were 13-14 times greater than the lowest sapogenin concentrations found (344 and 531 mg/kg dry matter, respectively). The results did not reveal systematic differences in sapogenin concentrations between the two seasons, or between samples harvested early or late in the same seasons, or between sapogenin concentrations in plants harvested at different sites. Cladosporium magnusianum was the predominant fungus found in the samples. The degree of fungal infection on the samples was in generally low, but the number of C. magnusianum colonies in the moist chamber preparations and fungal elements (conidia and hyphae) in leaf washings and on leaves tended to increase with time. Factor analysis and multiple regression analysis performed on the chemical and fungal results suggest that sporulation may have occurred in the fungi in response to increase in sapogenin concentrations.

[Neuralgia of the trigeminal nerve as first symptom of a primary central nervous system lymphoma of non-Hodgkin's type]

Primary central nervous system lymphoma of non-Hodgkin's type are distinguished from systemic non-Hodgkin's lymphoma because of their different pathobiological behaviour. Predisposing factors are pharmacologically induced immunosuppression and those referring to diseases. We present the case of a patient who was sent to hospital in case of emergency due to pain of one half of the face. The symptoms corresponded essentially to neuralgia of the trigeminal nerve. During course other neurological symptoms showed up. The right diagnoses of a primary central nervous system lymphoma of non-hodgkin's type was finally made post mortem. The case especially reveals the difficulties of diagnosis - including negative and confusing MRI-findings - and the variety of differential diagnosis of this also in not immunosuppressed persons more and more frequent kind of tumor.

[Quality of life after aortic valve replacement. Self-management or conventional anticoagulation therapy after mechanical valve replacement plus pulmonary autograft]

BACKGROUND

The improvement of quality of life gains increasing importance for the judgement of operative techniques. Besides the commonly used mechanical substitutes or bioprostheses for aortic valve replacement, the interest in the Ross procedure is growing. The aim of the study was to compare the quality of life after the Ross procedure with that after mechanical aortic valve replacement with two different anticoagulation regimes (self-management or conventional therapy).

METHODS AND RESULTS

Clinical, echocardiographic and quality of life investigations (SF-36) were performed in patients with mechanical aortic valve replacement and self-management of anticoagulation (group A, n = 20) or conventional anticoagulation therapy (group B, n = 20) and in patients after the Ross procedure (group C, n = 20). The mean ages were 59.5 +/- 9.2 (group A), 61.2 +/- 8.1 (group B) and 59.3 +/- 9 years (group C). Significantly lower values of quality of life (SF-36) were observed in group B compared with group A (5 of 9 subtests) and with group C (6 of 9 subtests) and also in the physical and mental health sum scales.

CONCLUSION

In this study the quality of life in patients after the Ross procedure and similarly after mechanical valve replacement and self-management of anticoagulation is superior to the quality of life after mechanical valve replacement and conventional anticoagulation.

Placental transfer of the estrogenic mycotoxin zearalenone in rats

In order to study the possible placental transfer of the Fusarium mycotoxin zearalenone (ZON), Sprague Dawley rats were treated with a single dose (0.74 mg/kg b.w.) of ZON i.v. on day 12 or day 18 of pregnancy, or intragastrically (i.g.) on day 18 of pregnancy. Samples of placenta, foetus, and maternal liver and spleen were collected for chemical analyses 0.3 h after treatment on day 12, and 0.3, 4, and 24 h after treatment on day 18. Three rats were used for each pregnancy day, administration route, and exposure time. The concentrations of ZON and its metabolites alpha- and beta-zearalenol (-ZOL) were determined quantitatively by high-performance liquid chromatography (HPLC) after incubation with beta-glucuronidase and purification on immunoaffinity columns. Tissue distribution was studied by means of whole body autoradiography at 4 and 24 h after treatment with tritiated ZON (750 microCi/kg b.w; 7.4 mg/kg b.w.) on day 18 of pregnancy. ZON and alpha-ZOL were transferred into the foetus on both gestational days. However, a delay in distribution into the foetus, relative to the maternal tissue, was observed. Beta-ZOL was below the detection limit in the foetus. No specific site of foetal accumulation of ZON or its metabolites was apparent. In the maternal tissues, the highest levels of ZON and of alpha- and beta-ZOL were found in the liver.

Prognostic significance of free gastrointestinal tumor cells in peritoneal lavage detected by immunocytochemistry and polymerase chain reaction

AIMS

The aim of our study was to identify tumor cells in peritoneal lavage comparatively with immunocytochemistry (ICC) and half-nested reverse transcriptase-polymerase chain reaction (RT-PCR) using carcinoembryonic antigen (CEA) as marker and to evaluate their prognostic significance.

PATIENTS AND METHODS

In 75 patients who underwent surgery for a carcinoma of the colorectum (n=49), stomach (n=17) or pancreas (n=9) and 13 patients with an abdominal aortic aneurysm (control group) the abdomen was irrigated with saline solution immediately after laparotomy. Cells were separated by Ficoll-density centrifugation and divided into 2 equal volumes for ICC and RT-PCR. For ICC cells were spun onto slides by cytospin centrifugation and stained with a monoclonal antibody (mab) against CEA using the APAAP method. For RT-PCR total RNA was extracted from the cells, transcribed into cDNA and amplified with CEA-specific primers. Lavages of 13 patients with an abdominal aortic aneurysm and blood samples of 6 healthy donors served as controls.

RESULTS

Immunostained tumor cells were found in peritoneal lavage in 23% (17/75) of all patients, whereas 63% (47/75) of patients gave a positive result by RT-PCR analysis. In the control group (n=13) no patient presented with tumor cells in ICC, however 5 of 13 (38%) showed amplified CEA-mRNA by RT-PCR, and so did one of six blood samples. Using ICC technique, we found significant correlations between detection rates and pT-, pN-, pM-categories as well as tumor stage. On the contrary, by RT-PCR significant correlations were observed only between pT- and pM-categories and detection rates. Detection of tumor cells in peritoneal lavage with both techniques was associated with poor prognosis. Moreover, these tumor cells are an independent prognostic factor and may have an influence on the development of peritoneal carcinomatosis.

CONCLUSION

ICC is a useful method for detection of tumor cells in peritoneal lavage. In contrast, half-nested RT-PCR cannot be recommended, as the detection rates are unproportionally high, obviously as a result of CEA-mRNA expression in nontumor cells.

[Thrombosed temporary vena cava filter]

The application of temporary vena cava filters for the treatment of deep venous thrombosis of the lower extremity has become increasingly important in recent years. The filters are supposed to guarantee temporary protection from more extensive pulmonary embolism. Occlusion of the filter system by a larger embolus as well as vena cava thrombosis including the filter struts present major therapeutic problems. We report on one patient in whom the temporarily inserted filter was trapped in a large vena cava thrombus and had to be removed surgically by caval thrombectomy. Because of possible complications such as the above, the indication for insertion of temporary vena cava filters requires thorough consideration. Their duration of stay should be as short as possible and should be limited to the high risk phase, not exceeding ten days.

[Severe obstipation in the mentally ill and disabled]

Severe constipation is a well recognized symptom amongst disabled or mentally ill patients. Characteristically, these patients live without bowel movements for days and present themselves with abdominal distension and fecal impaction. Inpatient treatment is necessary frequently. Due to intestinal obstruction, diagnostic approaches are often delayed because of lack of cooperation. Data of 94 disabled patients with severe obstipation are presented. 54 patients were admitted to inpatient treatment of constipation or bowel obstruction, 40 were treated for another diagnosis but had severe constipation which required intervention. Ileus or conservatively untreatable constipation led to 16 operations in 14 patients (polypectomy 2, rectopexy 1, cecostoma 5, left hemicolectomy 3, subtotal colectomy 5). Cecostomata are considered not to be effective as definite treatment whereas colonic resection resulted in daily bowel movements.

Circulating microemboli in patients after aortic valve replacement with pulmonary autografts and mechanical valve prostheses

BACKGROUND

The pulmonary autograft procedure (Ross) is now considered the gold standard for aortic valve replacement. One of its advantages is the freedom from macroemboli without anticoagulation. Whether this holds true for circulating microemboli, detectable as high-intensity transient Doppler signals (HITS), has not yet been verified.

METHODS AND RESULTS

We investigated 8 patients (2 women, 6 men; mean age, 50.6+/-17.9 years) after the Ross procedure, 9 patients (3 women, 6 men; mean age, 67.2+/-9.46 years) after aortic valve replacement with a mechanical valve prosthesis, and 12 young healthy volunteers by unilateral 1-hour recording of the middle cerebral artery on digital audio tape. Patients with extracranial carotid artery disease were excluded by color duplex sonography. During the off-line evaluation, the investigator was not aware of any patient details. No HITS were detected in healthy volunteers (95% confidence interval [CI], 0% to 26.46%). After the Ross procedure, 1 patient had 11 and 1 patient had 1 HITS (95% CI, 3.19% to 65.09%). All recipients of mechanical valves had HITS, ranging from 2 to 84 per hour (95% CI, 66.7% to 100%). Significantly more recipients of mechanical valves exhibited HITS than recipients of pulmonary autografts (P<.05) or control subjects (P<.05).

CONCLUSIONS

In contrast to mechanical valves, pulmonary autografts are seldom the source of microemboli, confirming the pulmonary autograft as the superior substitute for aortic valve replacement.

[A new probe holding device for continuous bilateral measurements of blood flow velocity in basal brain vessels]

The clinical relevance of transcranial Doppler sonography for the evaluation of cerebral perfusion and cerebrovascular regulatory mechanisms, as well as for the registration of embolic events, has increased considerably as a technique of non-invasive monitoring. The continuous measurement of blood flow velocities in two different vessel segments, either ipsilateral or contralateral, is limited by intricate probe fixation and positioning for optimal insonation of the vessel on the one hand. On the other hand probes are displaced frequently during anaesthesiological measures, so that continuous registration during induction of anaesthesia is not always guaranteed. In view of these limitations, a new probe-positioning and holding device has been developed and tested in a clinical study of patients undergoing cardiac surgery (n = 22). The newly designed probe-positioning and holding device allowed the unilateral adjustment and continuous measurement of the blood flow velocity in the middle cerebral artery (Vmca) from anaesthesia induction to endotracheal intubation in all patients (n = 9). This was possible in only 61.5% (n = 8) of the patients who were monitored via conventional mode of probe fixation (n = 13). The new method rendered possible the positioning, insonation and measurement in two vessel segments in 77.8% of the patients, in contrast to 53.8% of the patients where the conventional technique was used. The newly designed probe holding device meets all standard requirements from the anaesthesiological viewpoint, and facilitates the perioperative application of transcranial Doppler sonography for non-invasive monitoring.

Cerebrotendinous xanthomatosis without tendon xanthomas mimicking Marinesco-Sjoegren syndrome: a case report

A 39 year old patient with cerebellar signs, juvenile cataracts, and dull normal intelligence had cerebrotendinous xanthomatosis without tendon xanthomas, diagnosed previously as Marinesco-Sjoegren syndrome. Cerebrotendinous xanthomatosis was proved by a greatly increased excretion of bile alcohols in the patient's urine. Cerebrotendinous xanthomatosis is a sterol storage disorder due to an autosomal recessive inherited defect of sterol 27-hydroxylase characterised by high cholestanol concentration in multiple tissues. If tendon xanthomas are not present, a diagnosis of cerebrotendinous xanthomatosis will often not be made, unless biochemical tests are performed. The clinical features of cerebrotendinous xanthomas strongly resembles Marinesco-Sjoegren syndrome. Marinesco-Sjoegren syndrome is a autosomal recessive disorder characterised by the triad cerebellar ataxia, congenital cataract, and mental retardation. Although a late onset after the first decade of life favours cerebrotendinous xanthomatosis as the underlying disease, a definite distinction between cerebrotendinous xanthomatosis without tendon xanthomas and Marinesco-Sjoegren syndrome based on clinical presentation may be difficult. It is considered that some patients with Marinesco-Sjoegren syndrome reported in the medical literature had cerebrotendinous xanthomatosis without tendon xanthomas. This is of crucial clinical relevance, because, by contrast with Marinesco-Sjoegren syndrome, treatment for cerebrotendinous xanthomatosis is already available.