In vivo plasma membrane organization: results of biophysical approaches

In the last two decades, various biophysical techniques have been used to investigate the organization of the plasma membrane in live cells. This review describes some of the most important experimental findings and summarizes the characteristics and limitations of a few frequently used biophysical techniques. In addition, the current knowledge about three membrane organizational elements: the membrane-associated cytoskeleton, caveolae and lipid microdomains, is described in detail. Unresolved issues, experimental contradictions and future directions to integrate the variety of experimental data into a revised model of the plasma membrane of eukaryotic cells are discussed in the last section.

Tumour suppression induced by the macrophage activating lipopeptide MALP-2 in an ultrasound guided pancreatic carcinoma mouse model

BACKGROUND AND AIM

Carcinoma of the exocrine pancreas has a particularly poor prognosis. Therefore, novel therapeutic strategies such as immunotherapy are required. Here we investigated the immunomodulatory capacity of macrophage activating lipopeptide 2 (MALP-2), which binds to toll-like receptors 2 and 6 and induces activation of nuclear factor kappaB in monocytes. This causes the release of early stage leucocyte attracting chemokines and proinflammatory cytokines.

METHODS

MALP-2 was tested in a new orthotopic ultrasound guided pancreatic cancer mouse model. This model is close to the biological situation and avoids the stress and immunostimulation caused by laparotomy. Cells from the syngeneic, highly aggressive, and metastatic cell line Panc 02 were administered orthotopically, by ultrasound guidance, to C57bl/6 mice. MALP-2 was administered intratumorally or intraperitoneally and tumour growth, immune status, and leucocyte infiltration at the tumour site were determined.

RESULTS

We showed a tumour suppressive effect induced by a single injection of MALP-2. Median survival increased from 21 to 30 days (p<0.002). Combining chemotherapy (gemcitabine) with MALP-2 treatment caused further prolonged survival (median survival 27 days with chemotherapy alone v 37 days for combined treatment; p<0.0002). The life prolonging effect was paralleled by a significant increase in cytotoxic T cells, restoration of beta2 integrin expression on lymphocytes, and high expression of CD45RB on T helper cells. Immunohistochemical stains showed strong cytotoxic T lymphocyte and natural killer cell infiltration.

CONCLUSIONS

In conclusion, in a model of orthotopic pancreatic cancer in mice, we induced a tumour suppressive effect by treatment with a synthetic lipopeptide. Treatment with MALP-2 could be an option for immunotherapy in pancreatic cancer.

Search for extraterrestrial point sources of neutrinos with AMANDA-II

We present the results of a search for point sources of high-energy neutrinos in the northern hemisphere using AMANDA-II data collected in the year 2000. Included are flux limits on several active-galactic-nuclei blazars, microquasars, magnetars, and other candidate neutrino sources. A search for excesses above a random background of cosmic-ray-induced atmospheric neutrinos and misreconstructed downgoing cosmic-ray muons reveals no statistically significant neutrino point sources. We show that AMANDA-II has achieved the sensitivity required to probe known TeV gamma-ray sources such as the blazar Markarian 501 in its 1997 flaring state at a level where neutrino and gamma-ray fluxes are equal.

Control of atomic collisions by laser polarization

Atomic collision pairs in a light field form a microscopic interferometer. The light acts as the beam splitter and controls at the same time the amplitudes and phases of the interfering waves. We demonstrate the complete tunability using linear and elliptic polarization.

[Acrocyanosis: crucial symptom in a case of chronic diarrhea and weight loss]

The patient reported here was admitted because of severe dehydration caused by watery diarrhea. As underlying disease we found bacterial overgrowth of the small bowel due to myopathic dysmotility of the small bowel as a manifestation of CREST syndrome. An important clue to the diagnosis was the result of a ward round: the patient showed Raynaud's phenomenon when exposed to the cold at an open window airing the room. A leading tool for diagnosis and therapy proved to be small bowel manometry which is further discussed in this case report.

Do alterations of endogenous angiotensin II levels regulate erythropoietin production in humans?

AIMS

Recent evidence suggests a potential role of angiotensin II in the physiological regulation of erythropoietin (Epo) production. While the administration of exogenous angiotensin II (AII) has been used so far to study its effects, the role of endogenous AII has remained unclear.

METHODS

To alter endogenous AII in humans experimentally we used furosemide bolus injection as a short-term (study 1) and dietary salt as a long-term modulator (study 2). In an open crossover design, 12 healthy male volunteers received furosemide (F) 0.5 mg kg(-1) intravenously or placebo (P) in random order (study 1). With the same design, 12 volunteers received high-salt (HS), normal-salt (NS) and low-salt (LS) diet (study 2). Plasma renin activity (PRA) was analysed along with AII. Inulin and paraaminohippurate (PAH) clearances were used to indicate glomerular filtration rate (GFR) and renal plasma flow (RPF), respectively.

RESULTS

While F stimulated AII and PRA and decreased GFR and RPF significantly, no concomitant alteration of Epo was observed [AUCEpo: placebo 5709 +/- 243 (% of baseline x h), furosemide: 5833 +/- 255 (% of baseline x h); 95% confidence interval (CI) -608.4, 856.0; P = 0.73]. F decreased GFR (from 103.6 +/- 4.0 to 90.6 +/- 4.8 ml min(-1) 1(-1) 73 m-2; 95% CI 1.1, 24.9; P < 0.05), but not RPF (study 1). Correspondingly, LS stimulated and HS decreased AII and PRA significantly. HS increased GFR and RPF. Again, Epo concentrations were not affected (AUCEpo: normal sodium 44 +/- 6.7 mIU x day ml(-1), low sodium 39 +/- 2.4 mIU x day ml(-1), high sodium 48.5 +/- 6.1 mIU x day ml(-1); normal salt/low salt 95% CI -11.9, 21.9, P = 0.54; normal salt/high salt 95% CI -14.4, 23.3, P = 0.63; study 2).

CONCLUSIONS

We conclude that, at least in the physiological setting in healthy volunteers, increased concentrations of endogenous AII may not be a major factor of Epo regulation.

[Comparison of conventional enteroclysis, intestinal ultrasound and MRI-enteroclysis for determining changes in the small intestine and complications in patients with Crohn's disease]

BACKGROUND

Enteroclysis, intestinal wall ultrasound (IWU) and abdominal magnetic resonance imaging (MRI) are three established methods in the diagnosis of Crohn's disease (CD). To date, however, the three methods have not been compared in one patient collective.

AIMS

The present prospective study compared the relative performance of IWU, MRI and enteroclysis in determining the extent of disease involvement and intestinal complications in patients with CD both at initial diagnosis and during follow-up.

PATIENTS AND METHODS

Included in the present study were 48 patients with confirmed CD (age: 19-66 years) examined with all three methods between August 1999 and December 2000. IWU was performed in B-mode with a 4-7 MHz convex transducer head and a 5-12 MHz linear transducer head by an experienced examiner. At MRI, T1 and T2 weighted sequenced (Flash 2D before and after intravenous application of gadolinium DTPA or TSE) were acquired in coronal and transverse planes. Enteroclysis was performed using conventional biphasic technique. Interpretation was conducted on the basis of a standardized catalogue of findings.

RESULTS

Changes in bowel segments consistent with inflammation were identified in 41 of 48 patients. All three methods returned equivalent findings with regard to the length of inflamed bowel segments (IWU, range: 3-25 cm, mean: 12 cm; MRI, range: 3-25 cm, mean: 10 cm; enteroclysis, range: 3-30 cm, mean: 11 cm) and wall thickness (IWU, range: 4-10 mm, mean: 7 mm; MRI, range: 5-10 mm, mean: 7 mm; of nine patients with stenotic change, five were correctly diagnosed with IWU (sensitivity, 55.6%; specificity, 97.4%), four with MRI (sensitivity, 44.4%; specificity, 100%) and six with enteroclysis (sensitivity, 66.7%; specificity, 100%). Fistulae were correctly identified in five patients with IWU (sensitivity, 55.6%; specificity, 97.4%), in four with MRI (sensitivity, 44.4%; specificity, 100%) and in six with enteroclysis (sensitivity, 66.7%; specificity, 100 %) of a total of nine patients with confirmed fistula formation. Abscesses were correctly identified in five patients with IWU (specificity, 66.7%; specificity, 100%), in five with MRI (sensitivity, 83.3%; specificity, 100%) and in no patients with enteroclysis (sensitivity, 0%; specificity, 100%) in six patients with abscesses.

CONCLUSION

Both IWU and MRI identify extent, severity and intestinal complications with adequate diagnostic accuracy in patients with CD. Both techniques possess the potential for replacing enteroclysis in the work-up of CD. Enteroclysis should be reserved for the work-up of complex fistula systems.

Limits on diffuse fluxes of high energy extraterrestrial neutrinos with the AMANDA-B10 detector

Data from the AMANDA-B10 detector taken during the austral winter of 1997 have been searched for a diffuse flux of high energy extraterrestrial muon neutrinos. This search yielded no excess events above those expected from background atmospheric neutrinos, leading to upper limits on the extraterrestrial neutrino flux measured at the earth. For an assumed E-2 spectrum, a 90% classical confidence level upper limit has been placed at a level E2Phi(E)=8.4 x 10(-7) cm(-2) s(-1) sr(-1) GeV (for a predominant neutrino energy range 6-1000 TeV), which is the most restrictive bound placed by any neutrino detector. Some specific predicted model spectra are excluded. Interpreting these limits in terms of the flux from a cosmological distributions of sources requires the incorporation of neutrino oscillations, typically weakening the limits by a factor of 2.

Persistent vegetative state: evaluation of brain metabolism and brain perfusion with PET and SPECT

Patients in persistent vegetative state (PVS) after severe head trauma were investigated with 99mTc-ECD SPECT and 18F-FDG PET to further characterize the degree of brain damage and to obtain insight into changes of brain perfusion and glucose metabolism. 18F-FDG PET and 99mTc-ECD SPECT were performed in 16 patients in PVS. Quantitative PET data were compared with that obtained from seven normal controls. After spatial normalization into Talairach space, global grey matter values and regional data using predefined ROI sets were derived. For comparison of PET and SPECT, regional data were normalized to their individual mean grey matter values. Patients in PVS showed significantly lower values of cerebral glucose metabolism than did the controls. The mean reduction of grey matter values in cortical and subcortical structures was 58%, except in the vermis cerebelli, where only a reduction of 16% was found compared to the controls. Comparing the glucose metabolism and perfusion within the patient group, the pattern of both modalities was similar in the neocortex and internal ganglia. In the cerebellar hemispheres a relatively higher perfusion than glucose metabolism was found. The overall reduction of 58% of glucose metabolism in grey matter structures is in accordance with other PET studies investigating PVS patients with different disease histories. The relative preserved activity of vermis cerebelli seems to be an uncommon finding not described by other authors up to now.

[Multi-value regulatory systems for extracorporeal circulation]

Extracorporeal perfusion is the standard technique in cardiac surgery. It is controlled by perfusionists on the basis of their clinical experience and on the available data collected pre- and intra-operatively. But in spite of intensive monitoring postoperative complications occur. An appropriate control of the heart-lung machine (HLM) using an "autopilot" might improve the quality of heart-surgery and decrease postoperative complications. Hence, a mathematical model of a human circulatory system has been developed which provides much more information about haemodynamics, blood gases and acid-base status than standard monitoring. It has been implemented on a system which is capable of integrating measured data as input parameters in real-time in the simulation. Now, soft- and hardware control concepts based on the human circulatory system have to be developed which are able to control the HLM.